Interview Tunable White Light TRIAC Dimming

www.led-professional.com ISSN 1993-890X

Review LpR The leading worldwide authority for LED lighting technology information Jan/Feb 2011 | Issue 23

OLED Technology & Market Trends Digital LED Systems - Interview Tunable White Light TRIAC Dimming

EDITORIAL 1

Improved LED Drivers

During the last couple of years LED performance has shown rapid improvements and this has been the trigger for so many lighting innovations. But what are the requirements for LED driver and controller improvements?

Technically, lighting applications LED drive circuits have to keep up with those higher requirements. Fairchild PCIA lighting director Lee Peng said: “LED lighting driver circuits are focusing more and more on the stability of brightness, power conversion efficiency, the pursuit of higher efficiency, higher integration and smaller form factors”. Besides driver performance improvements, this key component is targeted with system requirements coming from the applications. One big topic is the interconnection with standard TRIAC phase cutting dimmers. For this reason, this issue contains a number of solutions. When it comes to advanced lighting systems, linking to interfaces such as DMX, DALI, Ethernet or other building management bus-systems seems to be important for modern controlling schemes. Physically, drivers should be able to work either wired or wireless with system controllers, sensors and other actors.

When looking inside an LED driver, many additional questions arise, like: What about the galvanic isolation? Which topology is the best approach for a specific application? What about the component stress and live time requirements? What about the off-line drivers in regards to mains regulations such as EMI and harmonic distortions? And also, should a driver be digital or analogue?

To answer the latter questions we have interviewed leading experts and companies in this field.

LED drivers are becoming more and more a key component in LED lighting systems. The quality, the flexibility and innovative solutions will depend strongly on sophisticated LED driving schemes. Software and software upgrading options may play an important role in the future. These developments are all made in a “standard-free” area – which makes it difficult to build up universal platforms and guarantee interchangeability.

Again, I would like to invite you to come and meet us personally at the “LED professional Symposium + Exhibition 2011” on Sept. 27-29 in the Festspielhaus (Festival House) in Bregenz, Austria. The symposium will be focusing on LED lighting technologies.

Technology is a key driver for innovation – that is the reason why we are bringing technology experts from the fields of LEDs, optics, drivers, ICs and thermal management together to present and discuss their “Winning Technologies”. The LpS 2011 will be the ideal platform for you to gather information, get key contacts and meet the leaders. Don’t forget: “Call-for-Papers” ends on February 1st, 2011.

Exhibitors and sponsors are welcome to reserve their packages. For detailed information please visit our symposium website: www.led-professional-symposium.com

We would very much appreciate your feedback about LpR. Let us know what you like or tell us how we can improve our services. Please keep in mind that you are also welcome to contribute your own editorials.

Yours Sincerely,

Siegfried Luger Publisher

Content Advertising Index

Cree p C2

Editorial p 1 News - PROJECTS p 4 LED professional Symposium p 3 Imprint p 64 News - PRODUCTS p 5 News - RESEARCH p 21 Recom p 11

Signcomplex p 17

EVENTS p 24 Infineon p 22 The Display Industry Drives OLED Technology p 24 by Alan R. Mills, LED professional Instrument Systems p 23

Kingbright Electronic Europe p 31 INTERVIEW p 28 "The Future of LED Systems is Digital" p 28 LED China p 37 Interview with Peter Deixler, Philips Eindhoven by Arno Grabher-Meyer, LED professional LED Lighting Taiwan p 41

Signcomplex p 46 APPLICATION p 32 Intelligent Lighting (Part II): From Definition to Implementation p 32 Guangzhou Int. Lighting Exhibition p 47 by Osama Mannan, Future Lighting Solutions LEDLink p 51

TECHNOLOGY p 38 OLED Insider p 55 Understanding the Pitfalls of Tunable White Light LED Systems p 38 by Madhan Kumar, Sachin Gupta, Cypress Semiconductors Curamik p 58

Lighting Japan p 59

ELECTRONICS p 42 Green Lighting Shanghai p C3 Triac Dimmable Primary Side Regulated Flyback p 42 by Michael Weirich,Fairchild Global Power ResourceSM Center EP Tridonic p C4

Facts about Dimming p 4 8 by Gregg Sheehan, Light-Based Technologies

Charge Controled LED Drivers p 56 by Jens Göhring, dilitronics

Needed Accuracy of an LED Power Supply p 60 by Christopher Richardson, National Semiconductors

2011LpS

LED Lighting Technologies

27-29 September 2011 Festspielhaus Bregenz / AUSTRIA

LEDs & OLEDs Optics Drivers Thermal Management Testing

Contact Luger Research e.U. / LED professional Austria +43 5572 394489 [email protected] NEWS PROJECTS 4

Xicato Spot Energy Gateway Modules are used in the LX2024 series Project at the Field luminaires from Lighting Services that Museum of Natural light up the T. Kimball and Nancy N. Brooker History in Chicago, Gallery at the Field Illinois Museum, Chicago The U.S. Department of Energy (DoE) has published a report from a demonstration conducted at the Field Museum of Natural History in Chicago, Illinois, to evaluate the feasibility of replacing halogen lamps with LED lamps. It forms part of the DoE’s GATEWAY project series which demonstrate real world experience of LEDs. The luminaires in the roof were built to order This GATEWAY study, carried out in late 2009, Bridge’s All-White by RENA – based on that company’s compares lighting performance, economic configurable Vincent Ledline fixture design performance, and energy consumption of Light Show with – with five cool white LUXEON Rebel LEDs halogen and LED accent lighting solutions. Luxeon-Based LED per module, a Carclo elliptical beam optic, Xicato Spot Modules in LX2024 series and a patent-pending louver system designed luminaires from Lighting Services Inc. were Fixtures by Primo to direct the beam as well as used in the study, carried out as a An all-white interactive LED light show that conceal the point source. collaboration between the The Field Museum plays nightly on the curvy sunroof of a of Chicago and the United States DoE pedestrian bridge in the former Soviet Union is RENA’s customizable off-the-shelf design represented by Pacific Northwest National powered by 1,208 custom LED fixtures offered rapid delivery that met Tbilisi’s tight Laboratory (PNNL) in late 2009. containing 6,040 high-power LUXEON Rebel timeline, a small footprint enabled by the LEDs from Philips Lumileds. The fixtures were compact LUXEON Rebel package, and In this project, 32 halogen track luminaires designed and built by Netherlands-based proprietary two-wire power/data connectivity used to light an enclosed gallery exhibit were Primo Exposures and RENA Electronica, with that expedited installation by eliminating three replaced with an LED system using 26 track all LEDs supplied by Future Lighting Solutions additional wires typically required for power fixtures. in the required 4200 K color temperature range and communication. Key findings include: in just two weeks to ensure color uniformity. Each of the 1,208 fixtures in the sunroof The LED system resulted in 63 percent energy The Bridge of Peace in Tbisli, Georgia – a city represents its own dimmable DMX channel savings compared to the halogen system and of 1.5 million – was designed by Italian and is programmed through a control produced comparable illuminance on the architect Michele De Lucchi with a lighting interface designed by RENA. The finished lighted artifacts. design created by France’s Philippe fixtures play four different lighting programs Martinaud. The bridge structure was built in every hour from 90 minutes before sunset The simple payback for the overall LED Italy and shipped to Tbilisi in 200 trucks. The until 90 minutes after sunrise, illuminating the system compared to the halogen system was lighting was installed on site in Georgia as the Mtkvari River in a dance of 21st century light roughly 3.3 years and was further reduced to bridge was being assembled. that serves a striking counterpoint to the only 2.4 years when considering the lower historic buildings on either bank. heat output from the LED luminaires and associated HVAC energy savings. The payback calculation considers the longer life of LEDs, lower maintenance costs and that fewer LED luminaires are needed to generate an equivalent amount of light compared to the halogen fixtures.

Because the LED luminaires used do not emit energy in the infrared or ultraviolet regions of the electromagnetic spectrum, they are expected to be less detrimental to some museum artifacts. The modern bridge with its dancing white lights forms a striking contrast with the historic buildings in this capital city of 1.5 million

New Bridgelux Pre- Cree Introduces The CXA20 LED array delivers 1050 lumens at 11 watts, or 2000 lumens at 27 watts, with a Wired LED Arrays Lighting-Class LED 3000-K warm-white color temperature. Samples are available now with standard lead Further Simplify Arrays to Accelerate times with production volumes targeted for Design Integration Indoor LED Lighting late Q1 calendar 2011.

Bridgelux Inc., a leading developer and Cree, Inc., a market leader in LED lighting, manufacturer of LED lighting technologies and announces the industry’s first lighting-class New Citizen LEDs for solutions, is further simplifying the LED light LED array. The XLamp® CXA20 LED array is source integration process for luminaire the first lighting-class array aimed at Lighting manufacturers with the introduction of new accelerating the LED lighting revolution and Citizen Electronics Co., Ltd. (Head Office: wiring options for its rectangular ES and RS can enable a 60-watt A-lamp equivalent while Fujiyoshida City, Yamanashi Prefecture. Array Series solid state light sources. This consuming just 11 watts. President: Yoshihiro Gohta) has developed option further enhances the plug and play the CL-L330 series (26W type) and CL-L340 simplicity delivered by these arrays, helping to series (41W type) of white LEDs for lighting, of facilitate quick design cycles and ease which the luminous flux per LED lamp is more system-level integration challenges for than twice that of the conventional model. Bridgelux customers.

With a compact 22 mm x 22 mm footprint, the new CXA20 LED array delivers up to 2,000 lm at 27 watts, with a 3000-K warm-white CCT

Citizen’s new and powerful CL-L330 series “We are impressed with Cree’s new XLamp (26W type) and CL-L340 series (41W type) of LED array,” said PK Li, OPTILED Lighting white LEDs for lighting All ES and RS Array Series products out of the Bridgelux portfolio are now available with the International, Ltd., Director of Product pre-wired option Development. “They combined lighting-class LED lighting has been in the spotlight as LED performance, unequaled in the market, with bulbs are commercially available. However, in The new wiring option provides two wires an ease-of-use that will enable us to quickly most cases it is difficult to provide enough soldered to the electrical contact pads on the develop both our new A19 lamp and down luminous flux for applications with only one LED arrays. This wiring option may be light products.” LED. Therefore, it is necessary to place two or ordered with all Bridgelux rectangular ES and more LEDs in lights. In such cases, the area in RS Array Series, which deliver between 800 With a single, uniform optical source, which LEDs are to be placed becomes larger to 4,500 operational lumens in all available compact 22 mm x 22 mm footprint, and and accordingly the size of the light also tends color temperatures. Providing pre-wired simple two-screw attachment, the CXA20 to become larger. In addition, there is another arrays simplifies the electrical integration of array can simplify the manufacturing process negative effect. When there are two or more the light source into the lamp or luminaire, for customers who require a single light sources, design to control light such as enabling Bridgelux customers to use component in their light-engine design. When that of the reflection plate becomes complex. interconnection methods common to the used in a traditional down light application, lighting industry and avoid introducing luminaires based on the CXA20 are delivering The newly developed products resolve these soldering processes in their factories. 38-percent more illumination than a 26-Watt problems by dramatically increasing luminous CFL or a 100-Watt incandescent bulb, while flux per LED and contribute to miniaturized “Our primary focus at Bridgelux is to make consuming a mere 14 Watts. lights and simplified optical design. It is also LED technology easy to use for our general possible to expand lighting applications lighting customers,” said Mick Wilcox, “Cree continues to bring the broadest family substantially where only one LED is used. Bridgelux product manager. “Providing this of lighting-class LEDs to market, ensuring that wiring option eliminates manufacturing lighting applications have optimized LED light High luminous efficacy: process steps and reduces product sources,” said Norbert Hiller, Cree vice In general, for LEDs, the more power supplied development risks and overall system costs. president and general manager, LED to a product, the lower luminous efficacy is Our customers can bring new energy- Components. “For lighting manufacturers likely to become. In response to this problem, efficient, high quality lighting products to seeking Cree lighting-class performance and we can combine high luminous flux and high market faster to meet the rapidly increasing also looking to simplify the design and luminous efficacy by mounting a number of market demand for solid state lighting.” manufacturing of their indoor LED lighting, the compact light-emitting dice, of which CXA series of LED arrays can be an ideal luminous efficacy is relatively high, in one LED solution.” package through utilization of “Citizen

Electronics” specialized high-density Achieve Efficient LedEngin Launches mounting technology. The new products, both 26W and 41W types, provide the same high Driving Circuit Design its Highest luminous efficacy as that of our conventional model (13W type) which has the highest in LED Lighting with Performance LED luminous efficacy of our products. Custom EdiPower®II Emitter Platform

5000K color temperature type: Series LedEngin, Inc., a leader in high performance 26W type: 104 lm/W, 41W type: 105 lm/W Edison Opto offers custom design options to LED lighting solutions, announces its latest 3000K color temperature type: its EdiPower®II series. Based on various and highest performance platform yet - the 26W type: 73 lm/W, 41W type: 73 lm/W application requirements, the multi-chips LZP-series. The multi- chip emitter generates EdiPower®II package can be adjusted in total up to 5500 lumen (CCT of 5500K) and Thermal resistance: power, operating current and driving voltage 3000lm (CCT of 3100K) in an unprecedented The highest level of heat dissipation has been of choice. compact 12mm x 12mm package. LZP-Series improved by 30% over that of the systems replace 35W metal halide (MH) bulbs conventional model. As a measure against or 50W high pressure sodium (HID) bulbs heat generation that has significant effects on achieving the high flux required in applications the service life of LEDs, we have achieved the such as High Bay lighting, architectural lowest level of thermal resistance of our LED lighting, street/area lighting and Stage & products, and effective heat dissipation Studio moving heads. processes are provided, such as transferring heat to a heat sink, etc. In addition, since the whole rear face of the LED package can be used as a heat dissipation route, it is possible to diffuse heat promptly. Edison Opto offers custom design options to its EdiPower®II series for total power, operating 26W type: 1.7°C/W current and driving voltage 41W type: 1.0°C/W Standard EdiPower®II includes four types of Color rendering: models: 4-6W, 8-15W, 16-24W and 30-50W. For white LEDs, there is a trade-off between The custom EdiPower®II package can be color rendering and luminous efficacy. Color designed to allow flexibility in adaption to rendering indices are set for the new products different power source driven parameters The LZP series emitter, copper Star PCB and by color temperature, based on main such that the package can enable operation TIR lenses are available for sampling and applications. in high voltage. This kind of specific package volume production not only simplifies the power circuit needed to 5000K color temperature type: drive the package, but also enhances the Key features of LedEngin LZP series: Ra67 (priority placed on luminous efficacy) power circuit efficiencies. • 24 LED dies configured in four strings of six 3000K color temperature type: dies in one series Ra83 (priority placed on color rendering) Power circuit design for the custom high • Maximum current of 1A per die totaling up voltage EdiPower®II series is especially easy to 90W power Applications: and cost-effective. Through proprietary LED • High luminous efficacy at 350mA per die of The 5000K-color temperature (cool color) package process and experiences, the 95lm/W (5500K) and 70lm/W (3100K) type is intended mainly for exterior illumination efficiency of the package can reach up to • Compact 12mm x 12mm form factor for where priority is placed on luminous efficacy. 120lm/W; while the power circuit solution can high luminous density For example, this type is suitable for also yield higher efficiency because less heat • L70 lifetime > 50,000 hours streetlights, projectors and advertising lights. is being generated by the difference in power • Available in CCT 2700K, 2900K, 3100K, The 41W type provides, with one LED lamp, loss associated with voltage drop from the 4100K and 5500K the same high luminous flux as that of a input source to the LED package. • Typical CRI of 85 and R9 of 30 for true color general 100W mercury lamp. Therefore, it is Custom high voltage designed EdiPower®II is rendering expected to reduce power consumption by ideal for application together with integrated • Color point stability 7x better than the about 60%. The 3000K-color temperature circuit design within luminaries or light bulbs. requirement of Energy Star (warm color) type is intended mainly for For the generated heat from the circuit to be • Emitter junction to case thermal resistance interior illumination where priority is placed on reduced, the integrated heat-sink would result of 0.35K/W color rendering. For example, this type is in higher heat capacity and dissipation. Heat • Offered with or without glass dome suitable for down lights for base lighting or from LEDs would sustain a longer lifetime for • LedEngin designed high efficiency TIR lens spotlights for product rendition. The 41W type reduced temperature generated from the products with 15°, 23° and 35° beam provides, with one LED lamp, the same high power circuit. The number of applications for angles luminous flux as that of a general 150W EdiPower®II include down-light and retrofit • LedEngin-designed, extremely low thermal halogen lamp. Therefore, it is expected to light bulbs. resistance, copper core PCB (0.1K/W) reduce power consumption by about 70%. mounting option to minimize design time

LedEngin high lumen density products are design allows a high packing density, making XP-E HEW LEDs are optimized to lower initial complemented with proprietary TIR high- it possible to combine several ASELight STAR costs for diffuse lighting applications, such as efficiency optics to produce maximum lumens modules at the same time, like a mosaic, in LED replacement lamps and down-lights. For in beam for superior Lux on TargetTM order to achieve large lighting surfaces with a example, an A-19 lamp that uses XP-E LEDs performance. LedEngin LZP-series when wide variety of contours. could be re-designed to use half as many XP-E coupled with LedEngin TIR optics exceeds LEDs while maintaining the same efficacy. the luminance of competing LED solutions by 6-10 times. The compact optical system “One of the major barriers to LED lighting overcomes a major challenge in flood and adoption and design remains upfront cost,” spot lighting applications that cannot be said Paul Thieken, Cree director of marketing, achieved with larger LED sources or current LED components. “By enabling designers to technologies such as MH or HID. Equally use brighter, precisely-optimized LEDs for important, the single high lumen density each particular application, Cree is helping emitter in combination with a single high lower costs and further simplifying and efficiency TIR optic produces a superior light shortening the LED fixture design cycle.” quality, homogeneous beam pattern and crisper image for a more natural perception of Asetronics manufactures a successor for XLamp XP-E High Efficiency White LEDs are the light. Osram’s obsolete OSTAR, the ASELight STAR the first high-power LEDs featuring Cree’s new Direct Attach™ LED technology. Direct “With the introduction of our new LZP-series, The ASELight STAR can be easily fitted with Attach technology is Cree’s unique, next- LedEngin pushes the lumen density screws or clips. The power cable can be generation LED chip technology that delivers performance to record high levels. With soldered or connected using clips. higher flux, lower forward voltage, and lower brightness performance equivalent to MH and thermal resistance. HID levels, our customers can take advantage With color temperatures of 3000K (warm of our robust packaging and long lifetimes to white) and 6500K (cold white) it can be used “With 500 percent more die-attach area and improve the overall cost of ownership for a for a wide range of applications. Additional an order-of-magnitude less die under-fill, new class of lighting applications”, said color temperatures will be added at a later Direct Attach technology is far more robust Xiantao Yan, Founder and CTO of LedEngin. date. than any other LED flip chip technology in the “Our LZP-series emitters have the same market today,” said John Edmond, Cree known robustness, lumen maintenance director of advanced optoelectronics. “For our performance, color quality and color point New High-Efficiency customers, these attributes, combined with stability that customers have come to value ® the performance advantages of Direct Attach with LedEngin products.” Cree XLamp LED technology, can translate to brighter, more reliable lamps and fixtures, developed at a Can Reduce Initial lower cost.” ASELight STAR to Fixture Cost XLamp XP-E High Efficiency White LEDs Replace Discontinued Cree, Inc. announces the commercial deliver up to 148 lumens in cool white (6500K) OSRAM OSTAR availability of XLamp® XP-E High Efficiency and 114 lumens in warm white (3000K) at 350 White (HEW) LEDs. The new high-efficiency mA. In addition to light output and efficacy At Electronica 2010 in Munich Asetronics components extend the light output and improvements, XP-E HEW LEDs feature a introduced the ASELight STAR, a replacement efficacy of the award-winning XLamp XP-E reduced thermal resistance of 6 °C/W. XP-E product for OSRAM OSTAR Lighting. The LED family, enabling fixture designs that can HEW LEDs are available in the same white successor product has been developed in use up to 50 percent fewer LEDs, which can variations as XP-E LEDs, including Standard collaboration with OSRAM Opto help drive down costs for fixture and bulb White, Outdoor White and 80-CRI White. Semiconductors on the proven basis of the manufacturers while delivering the same previous LED and will be produced and sold system performance. XLamp XP-E High Efficiency White LEDs are exclusively by Asetronics. available now in sample and production quantities with standard lead times. IES The new OSRAM OSTAR Lighting Plus LED LM-80 data for measuring lumen light source is the basis for the ASELight Star. maintenance of LED light sources, for XP-E It is equipped with the latest OSRAM chip HEW LEDs, is targeted for availability in generation and guarantees well-known February 2011. reliability. The module is based on the identical platform (Hexagonal) as the previous product, OSTAR Lighting. This makes it possible to use the new product as a 1:1 replacement in an existing system. The new Cree’s updated XLamp XP-E not only provides higher efficiency and luminous flux but also four-chip version achieves a brightness of lower thermal resistance to improve thermal 700lm at 700mA. The proven hexagonal management

New LED Vega Series The differences between the two models are: GL-MR1605WH-WW has a Correlated Color from GlacialLight Temperature (CCT) of 3000K while GL- GlacialLight, a sub-division of the experienced MR1605WH-CW offers 5000K; the Luminous technology manufacturer GlacialTech Inc., is Flux of GL-MR1605WH-WW and GL- excited to release an all-new, environmentally- MR1605WH-CW are 250 lm and 360 lm, friendly product – the LED Vega Series, a respectively; and finally, the warm white direct replacement for halogen AR111 lamps. displays an illumination of 250 lux at 1m while With GlacialLight’s specially-designed LED the cool white bulbs are brighter with 360 lux driver on board, the brand-new GL-AR111 at 1 m. LED Vega Series is compatible with all electronic transformers and can be placed in Specifications: NeoPac 8 inch silicon-based wafer level any halogen AR111 lamp socket immediately. • Power Consumption: 12W package (WLP) for LEDs delivers 500,000 • CCT: 3000K/6000K maintained lumens on a single wafer • Luminous Flux (Lm): 520/650 • Luminance(lm/W) : 43/54 This 8 inch semiconductor manufacturing • Beam Angle: 25º process is for NeoPac’s unique ultra-high- • Input Voltage: 12V AC/DC power, multi-chip-module, single-packaged • CRI > 75 and point-like-source LEDs, or the so-called • Base: G53 NeoPac Emitter. By coupling the NeoPac Emitter together with its patented, highly Features: effective micro heat pipe based heat- • Direct replacement for any halogen AR111 dissipation mechanism, a sustainable LED lamp standard light source, so-called NeoPac Light • Compatible with electronic transformers Engine is available for LED general lighting. without LED drivers The integrated ultra high brightness NeoPac The LED Vega Series is a direct replacement for • Low power consumption – energy-saving Light Engine is actually made by a system-in- halogen AR111 lamps green product package (SIP) approach. • Power conversion efficiency > 80% The halogen AR111 lamps generally require • Long lifetime > 50,000 hrs LEDs WLP (Wafer-Level-Package) is a more energy and have significantly shorter • Eco-friendly: RoHS Compliant, No UV, no semiconductor process that LED chips can life-spans than GlacialLight’s brand-new LED IR, & no mercury be directly mounted along with a phosphor Vega Series. In fact, GlacialLight’s GL-AR111 • For indoor use only coating, wire bonding, and packaging LED Vega Series lamp has extremely low-level processes on a whole silicon wafer. More than of heat radiation so users can actually see a Design of LED lighting products is based on 480 pcs multi-chips-module (MCM) consisting reduction, not only in their lighting energy bill three core technologies including electrical of 3,840 pcs LED power chips can be but their cooling bill as well. Rated at over design (LED drivers), mechanical design automatically mounted for the NeoPac Emitter 50,000 hours of life, once a GL-AR111 LED (cooling devices), and optical design (lamp on a single 8 inch silicon wafer. Vega Series lamp is placed, it is going to be a holders), respectively performed by the long-enough time before the question of GlacialTech family. With the three core NeoPac plans to bring this advanced LED replacing even crosses your mind. Able to technologies in hand, GlacialTech packaging technology into mass production in accommodate an input voltage of 12V±10% manufactures excellent LED lighting products 2011. “The 8 inch WLP approach will drive the provided by either an AC source or a DC you can trust. advancement of NeoPac’s currently far- source to power the inbuilt LED driver, the beyond-leading technology for LED GL-AR111 LED Vega Series are more illumination far ahead into a new era”, convenient and flexible than the halogen NeoPac Unveiled emphasized Jeffrey Chen, Chairman and CEO AR111 lamps confined to an AC source. 8 inch Wafer of NeoPac Opto. Thinking of the environment, GlacialTech Level Packaging Each NeoPac Emitter can emit maintained designed the GL-AR111 LED Vega Series to lumen at 1,000 lm. Most importantly, the contain no hazardous chemicals, such as Technology for LEDs standard light source will suitably fit any mercury, or harmful radiation emissions such secondary optics design for a variety of LED as UV or IR, making these more eco-friendly Illumination illumination applications owing to the intrinsic than the traditional incandescent lighting NeoPac Opto, Inc. a Taiwan based merits of the lighting characteristic of fixtures. With a power conversion efficiency of technology-driven LEDs lighting company point-like-source. Furthermore, the effective greater than 80%, GlacialLight is extremely recently announced its newly developed "useful life" (L70) of such a light engine can excited to give consumers the LED Vega technology on 8 inch silicon-based wafer level sustain much longer than 60,000 hours. By Series – an economically and environmentally- package (WLP) for LEDs illumination, which is this new WLP manufacturing technology, it’s friendly lighting solution. derived from its patented NeoPac Universal possible to deliver an amount of higher than Platform and LEDs Standard Light Sources. 500,000 maintained lumen on a single 8 inch

silicon wafer. According to NeoPac’s Essentia luminaires earned acceptance in the Qnuru Unveils the sustainable technology roadmap and LED Illuminating Engineering Society (IES) 2010 chips’ lumen efficacy improvement, it is Progress Report. Inclusion in the notable Lighting Industry’s estimated that the package on the same 8 report recognizes the product as a unique inch silicon wafer can deliver a total and significant advancement to the art and Highest Performance maintained lumen output of up to one million science of lighting. Essentia was presented at Consumer-Ready (1 M) lumen 2 years later. This technology is the annual IES conference held November 8 about to enable the mass-production of LED in Toronto, Canada. LED Bulbs lighting, which can substantially reduce the Qnuru™, the premier provider of energy manufacturing cost in quantity. The series of luminaires can be easily efficient digital lighting solutions, today upgraded as LED technology advances with launched the Qnuru Prism™ product family of a replaceable light engine and optics. The 44 LED bulbs for residential, office and light BetaLED’s Essentia™ complete line includes an unbeatable LED commercial buildings. Designed to fit the 4.7 performance package and is designed with billion U.S. light sockets, Prism LED bulbs Downlights Offer exceptional features: consume one-fifth the energy of incandescent Largest LED lamps, generate up to 1,080 lumens and, with • Standard 0-10V dimming control normal use, have a service life of 50,000 Selection and Highest • 4-, 6- and 8-inch square and round hours, compared to 2,500 hours for apertures incandescent bulbs and 15,000 hours for Lumen Package • 1,200 to 5,000 lumens delivered compact fluorescent lamps (CFLs). Stylishly BetaLED is producing a new line of interior • Multiple color temperatures available designed to resemble traditional light bulbs architectural downlights for commercial and • Narrow, medium and wide distribution and fit standard sockets, the Prism product high-end residential use. Essentia interior LED patterns family includes A, B, MR, PAR, R, and T8 downlights offer a variety of warm interior • 45 degree cut-off Series LED bulbs. Prism LED bulbs are correlated color temperatures (CCT), a wide • L70 of greater than 50,000 hours available in warm white, cool white and range of LED counts, an unbeatable lumen dimmable variants. package and wide, medium and narrow The new Essentia interior luminaire series optics including adjustable and wall-wash. joins the successful BetaLED product family The versatile product selection allows of well-known exterior brands THE EDGE® Essentia lighting to be tailored for each unique area luminaires, LEDway® streetlights, and application. 304 Series™ luminaires for interior and exterior use. Essentia luminaires are currently “We merged our best practices in renowned available for distribution in North America. BetaLED product benefits with years of Since 2007, BetaLED has ushered in LED innovation from our Kramer interior luminaires development and set industry milestones with to develop the best and most complete line of a commitment to reduce energy use and interior LED luminaires,” said Christopher improve lighting performance through the Qnuru’s Prism LED bulbs series covers all Ruud, president of Ruud Lighting. “The advancement of LED luminaires. BetaLED relevant form factors from the small MR11 to Essentia product brings to market what continues to raise the bar for design and A19 globe and PAR lamps customers want out of an ideal interior LED performance excellence as technology and light source. Essentia delivers advantages product lines grow and expand. Based on Cree XR-E LEDs, Qnuru’s Prism that we haven’t seen offered in the LED bulbs generate negligible heat, turn on commercial industry.” instantly, are flicker free, and emit no UV radiation. All Prism bulbs are rigorously One-for-one tested, UL Listed, RoHS Compliant, approved replacement of 500 Watt T4 by CE and come with Qnuru’s 3-year Quartz luminaires replacement guarantee. Because they contain with 15 Essentia no mercury, they can be responsibly recycled medium distribution with other metals and glass. The complete downlights (42 Prism product line can be purchased from LEDs each) at St. Catherine’s High Authorized Qnuru Dealers or online through School Auditorium the Qnuru website. Qnuru is part of the Noribachi Group, a clean technology private equity firm.

Lights Out for the 60W Incandescent Bulb: Qnuru’s Prism LED bulbs are designed to address the demand for energy efficient, non-toxic alternatives to today’s incandescent

bulbs, which are only 10% efficient, wasting lifetimes. Directional applications, such as 90% of their energy to heat dissipation. those currently served by incandescent, PAR, Incandescent bulbs in the U.S. will be phased and reflector lamps and which have seen out beginning in 2012 because of a relatively little acceptance of CFL solutions, government mandate that all general-purpose are providing the newest solid business case light bulbs become 30% more energy efficient for LEDbased replacement lamps. than current incandescent bulbs. All LEDnovation lamp models are tested for The centerpieces of Qnuru’s Prism product photometric performance in accredited line are its A Series 60W replacement LED third-party labs according to IES LM-79 bulbs that come in two models: Opal A19 and requirements, with reports available online. All Topaz A19. The highest performance 60W lamps meet UL 1993, UL 8750 and CSA 84 equivalent screw-in LED bulb available, safety standards. These commercial grade Qnuru’s Opal A19 provides an output ranging models are rated for a 50,000-hour lifetime from 590-630 lumens while using only 9 watts and carry an industry-leading 5-year warranty. of energy. The Qnuru Topaz A19 LED bulb The EnhanceLite® LEDH-A19-60-1-27D-I was provides an output range of 420-520 lumens starting production and shipping in mid while consuming only 6 watts of energy. Both LEDnovation’s EnhanceLite® A19 Generation-2 December 2010. products come in a variety of color ranges LED lamps, the LEDH-A19-60-1-27D-I, offers a and with dimming capabilities. 615-lumen output at a warm 2700K color temperature Edison Opto Unveiled “Over the last three years we have developed New Light Source at the lighting industry’s highest performance Main Features: LED solutions with our Vector 75-1500 watt • 615 lumen output with only 6.15 W power the LED EXPO 2010 retrofit product line,” commented Rhonda consumption Dibachi, President and CEO of Qnuru. “It was • Efficacy exceeding 100 lumens/watt verified in New Delhi a logical step to migrate our industrial- at NIST accredited third party lab Edison Opto showed a whole new lighting strength LED know-how to our Prism line of • 90% energy savings compared to a source which focuses on bulbs and low wattage, consumer-ready LED bulbs. No 60-watt Incandescent commercial application. For a long time other lighting company offers LED lighting • 53% energy savings compared to a 13-watt Edsion has been making efforts to develop solutions that span from 6 to 1,500 watts and CFL, without harmful mercury T.E.M.O.(Thermal management, Electrical 100 to 30,000 lumens. Whether you are a car • 2700K dimmable warm white with CRI scheme, Mechanical refinement, and Optical dealership with 1,000 watt metal halide lights greater than 90 optimization) as its R&D capacity. LDMS or a homeowner looking to replace a 60 watt • Designed for downlight and recessed (Lighting Design Manufacturing Service) is an bulb, we have the right size LED solution.” fixtures integrated program derived from the T.E.M.O. in providing customers various LED According to Israel J. Morejon, CEO of components and modules to meet their LEDnovation Sets LEDnovation, “Our milestone achievement of needs. 100 lumens/watt represents the promise of Landmark with LED lighting as the highest efficiency 100lm/W Warm lamp-level light source. We continue to invent, commercialize and deliver LED lighting White LED A19 innovations that aim to make energy- inefficient light bulbs obsolete. LEDnovation Replacement Lamp has conscientiously applied LED technology, LEDnovation, a leading innovator in LED power management expertise, and our lighting and replacement lamp technology, proprietary color mixing technology, including announced the introduction of the industry’s deeper red saturation, to achieve this highest efficiency and first high-quality 100 precedent-setting level of quality and lumen/watt, warm white, dimmable A19-type performance. replacement lamp. The first in the series of EnhanceLite® A19 Generation-2 LED lamps, This EnhanceLite® A19 Generation-2 lamp the LEDH-A19-60-1-27D-I offers a 615-lumen further expands the Tampa, Florida based output at a warm 2700K color temperature, company’s full portfolio of LED-based delivering “on-the-target” light levels replacement lamps, including the recently Edison Opto’s new lighting source focuses on equivalent to a 60-watt standard introduced line of industry-leading PAR and bulbs and commercial application incandescent or 13-watt compact fluorescent MR16 replacement lamps. LED lighting in standard downlight applications. continues to gain acceptance for a growing The new lighting source (as shown) includes number of applications by providing superior the latest EdiPower II ® which can reach up performance, higher efficiency and longer to 120lm/W, Edixeon® series with light

NEWS PRODUCTS 12

Application diagram efficiency of 130lm/W, and Federal series of of the FAN6920MR 100lm/w. Edison Opto stresses the core that offers integrated integrated technology. The high-efficiency critical-mode and components with secondary lens, heat sinks, quasi-resonant and power circuits can be used widely in current-mode flyback PWM controller commercial lighting, indoor lighting and design outdoor lighting with the result of satisfying the demand of the growing market in India.

With India’s rapid urbanization and industrialization, a large number surges in the requirement for electricity and lighting loads 12%. That is why energy-saving LED lighting, the replacement of traditional lighting, is needed urgently. The Grameen Surya Bijli Foundation indicates that the 2009 output Key Specifications: Fairchild enables engineers to drive innovation value in lighting is only 4,900 million USD that • Integrated PFC and Flyback Controller in their designs by developing solutions like increased 3.1% compared to the previous • Critical-Mode PFC Controller the FAN6920MR, which is part of a family of year. The annual growth rate in 2015 will reach • Zero-Current Detection for PFC Stage integrated critical mode PFC and quasi- 41.5%. In addition, a survey shows Indian • Quasi-Resonant Operation for PWM Stage resonant current mode PWM controllers. import demand for lighting products at more • Int. Minimum tOFF 5µs for QR PWM Stage These devices integrate functionality, increase than 5,000 million U.S. dollars and it is • Internal 5ms Soft-Start for PWM performance and provide full protection while continually increasing. Accelerating the • Brownout Protection lowering component counts, simplifying development and distribution for the huge • High /Low Line Over-Power Compensation design and reducing bill of material costs. business opportunities in the Indian market, • Auto-Recovery Over-Current Protection Edison unveils a series of new active lighting • Auto-Recovery Open-Loop Protection sources. According to different areas Edison • Externally Auto-Recovery Triggering DC/DC LED Driver responds to customer applications by • Adjustable Over-Temperature Latched showing comprehensive product capabilities • VDD Pin and Output Voltage OVP (Auto- with Wide Input Range and strengthening international awareness in Recovery) With the release of AMLD-Z, Aimtec launches the high-power LED market. • Internal Temperature Shutdown (140°C) the third series in its line of DC/DC LED Drivers. Offered in a DIP24 package, the The FAN6920MR combines a power factor AMLD-Z are feature rich LED drivers that Fairchild correction (PFC) controller and a quasi- meet the rigorous demands for environment resonant PWM controller for a cost effective friendly LED lighting solutions. Semiconductor’s design that uses fewer external components. PFC/PWM Controller For PFC, the device uses a controlled on-time technique to provide a regulated DC output for Dual-Switch voltage and to perform natural power factor correction. With an innovative total harmonic Flyback Topologies distortion (THD) optimizer, the FAN6920MR Power engineers, especially those involved in can reduce input current distortion at All-In-One (AIO) PC power, Slim Pack PC zero-crossing duration to improve THD adapters, LCD TV and LED lighting designs, performance. require a dual switch flyback topology that provides the higher efficiency and increased For PWM control, the FAN6920MR provides Aimtec’s AMLD-Z series DC/DC LED driver energy savings required by government several functions to enhance the power deliver up to 1000mA output current, an input regulations – something that LLC or single system performance including extended range of 8:1, while providing 97% efficiency flyback solutions cannot provide. Developed valley detect up to the 12th valley cycle for to answer this need, Fairchild reduced switching frequency, improved light From a wide (8:1) input range of 7-60VDC, the Semiconductor’s (NYSE: FCS) FAN6920MR, load efficiency, green-mode operation, an AMLD-Z series of LED drivers provide an integrated critical mode PFC and quasi- internal 10ms soft start and high/low line constant output currents ranging from 150mA resonant current mode PWM controller, over-power compensation. to 1000mA, generating from 6 watts to meets regulatory requirements by providing 48watts of power to maintain the constant >90 percent efficiency and <300mW at no Additionally, the device provides many color and brightness that is required by load for increased power savings. protection functions including brownout, today’s most demanding LED applications. secondary-side open-loop and over-current with auto-recovery, external auto-recovery Feature rich, the AMLD-Z series provides protection triggering and internal over- remote ON/OFF control function in addition to temperature shutdown. both PWM and analog voltage dimming

control (0 – 100%). Open and short circuit The market scale of the LED lighting field is protection works continuously until the short expected to grow substantially, spurred circuit condition is resolved, protecting the mainly by the adoption of LED lighting as a converter, the LED lights, and the converter’s replacement for incandescent light bulbs. input circuit from extremely high currents a Since LEDs use direct current drive, it is short to ground causes. Diodes’ AL8400 LED driver application circuits necessary to convert the commercial using MOSFET (left) and Bipolar transistors alternating current (AC) power supply to direct Boasting efficiencies as high as 97%, (right) current (DC). This requirement to add AC-DC Aimtec’s LED drivers are designed to be as conversion circuits has brought to the fore, a reliable as the LEDs they drive, allowing them The AL8400 has a very low 200mV current demand for elements designed to address to be used at an operating temperature of sense voltage which reduces operating issues such as cost, conversion efficiency, -40°C to +85°C at full load for compatible with voltage overhead and increases efficiency and power factor. In response, a variety of a wide range of LEDs applications from a compared with traditional solutions. Its open control methods for LED lighting drivers have variety of manufacturers without the need for collector output drives the external pass been announced. Using exclusive voltage any external components. transistor allowing it to regulate LED current step-down control technology, Renesas from tens of mA to above an A. Electronics has succeeded in developing an RoHS compliant, the AMLD-Z series of LED LED driver IC that delivers high efficiency and drivers is competitively priced starting at Using an external pass transistor allows a high power factor at low cost. $14.26/1000+pcs with samples available from power dissipation and maximum drive stock and can be ordered through one of capability to be optimized. Longer LED chains Main Features: Aimtec’s franchised distributors. needing significantly more than 18V can be • Reduced system cost driven with minimal additional external Renesas Electronics’ exclusive voltage components. step-down control technology (single-stage) Diodes Linear provides a high line-to-ground voltage. In The LED driver’s low temperature drift and 3% addition, the ability to select low-voltage Constant Current reference voltage at 25ºC outperforms most MOSFETs (voltage tolerance of only 500 Driver Provides existing linear solutions while keeping system volts (V) to 300 V, rather than the typical costs down at the same time. The AL8400 700 V) further contributes to lower system Versatile Control for linear controller in its small footprint, low cost. profile SOT353 package, delivers power • High efficiency and a high power factor LED Applications density that is superior to many common The use of Renesas Electronics’ exclusive Diodes Incorporated, a leading global package alternatives and provides a low EMI high-voltage control and critical-conduction manufacturer and supplier of high-quality solution. mode enable zero-current switching at application specific standard products within turn-on and switching in a low drain-source the broad discrete, logic and analog voltage state. As a result, the new LED semiconductor markets, introduced the Renesas Electronics driver IC enables reduction of power loss AL8400 linear LED driver controller. The Introduces R2A20134 during switching and achieves the industry- AL8400 is designed to tightly regulate LED leading power factor of 92 percent by current via an external transistor across wide LED Driver IC for LED reducing the power loss during switching. variations of high brightness LEDs. Suiting a In addition, critical-conduction mode allows broad range of LED chains in illumination, Lighting PFC (power factor correction) control using indication or signage systems, the controller Renesas Electronics, a premier provider of few external components and realizes a can directly operate from 2.2V to 18V and will advanced semiconductor solutions, power factor of 0.9 or higher. drive either N-channel MOSFET or NPN announced the availability of its R2A20134 • Support for various LED control modes Bipolar transistors. LED driver IC that supports LED lighting A variety of control modes can be achieved applications with high efficiency and a high by changing the configuration of the Features: power factor at low cost. externally connected elements. Examples • Low reference voltage (VFB = 0.2V) include buck-boost control, average- • -40 to 125ºC temperature range current control, peak-current control, and • 3% Reference voltage tolerance at 25°C constant-input-power control. • Low temperature drift Renesas Electronics’ R2A20134 LED driver • 0.2V to 18V open-collector output IC also can be employed in TRIAC dimmer • High power supply rejection (> 45dB at applications by applying a voltage matched 300kHz) to the TRIAC phase to the FB (feedback) pin for constant-current control. The Applications: company additionally supplies drive • Isolated offline LED converter MOSFETs meeting a variety of power and • Linear LED driver performance requirements. Renesas’ R2A20134 LED driver IC provides high • LED signs efficiency and high power factor • Instrumentation illumination

National intelligent dimming decoder, ensures smooth, Sharp Controller consistent illumination across the full dimming Semiconductor range. This combination of features provides for Indoor Lighting- the most efficient and uniform dimming Introduces LED Driver performance in the industry. The LM3450 Adjusts Brightness with Extraordinary LED driver also provides active power factor and Color correction, ensuring a high power factor that Phase-Based complies with residential and commercial Sharp Corporation has developed and will Energy Star standards. introduce the LR56001 LED controller for LED Dimming Capabilities ceiling lights, allowing users to adjust the National Semiconductor Corp. introduced a The LM3450 LED driver regulates an accurate brightness and color of three types of LEDs: new LED driver with the industry’s best output while maintaining excellent power cool white, warm white and night light. phase-based dimming performance for factor at the input. The integrated phase high-brightness light-emitting diode (LED) dimming decoder interprets the phase angle applications. The LM3450 LED driver and remaps it to a 500 Hz PWM output to dim integrates active power factor correction the LEDs. This combination of features is ideal (PFC) and phase dimming decoding to for implementing a phase dimmable off-line provide uniform, flicker-free illumination across LED driver for 10 Watt to 100 Watt loads. a wide, programmable dimming range. This member of National’s PowerWise energy- Technical Features: efficient product family is well-suited for use in • Critical conduction mode PFC Sharp’s LR56001 IC is a three channel LED high-performance, phase dimmable, 10 Watt • Over-voltage protection controller for indoor lighting to 100 Watt LED fixtures. • Feedback short circuit protection • 70:1 PWM decoded from phase dimmer Major Features: Residential and commercial lighting • Analog dimming • A three-channel independent control allows applications that interface with phase-based • Programmable dimming range brightness and color adjustments to be dimmers require circuitry that can correctly • Digital angle and dimmer detection made for three types of LED ceiling lights decode a phase-chopped waveform to • Dynamic holding current (cool white, warm white, and night lights). provide proper dimming of the LEDs. • Smooth dimming transitions • Built-in chopper circuit contributes to Dimmable LED drivers available today • Low power operation greater energy efficiency for LED lights. do not always meet the minimum current • Start-up pre-regulator bias requirement for forward phase or TRIAC- • Precision voltage reference The demand of long-life, energy-saving LED based dimmers, causing the dimmer to lighting is growing and its use is expected to shut off or “misfire” during operation. This Applications: expand for indoor lighting fixtures, such as causes inaccurate decoding of the phase • Dimmable downlights, troffers, and lowbay ceiling lights and light bulbs. angle resulting in flicker, particularly at very • Indoor and outdoor area SSL low dimming levels. To compensate, today’s • Power supply PFC Specifications: drivers reduce the LED dimming range or LED controller for indoor Product continuously burn power to keep the dimmer Other benefits include an analog adjust input lighting from misfiring. to allow for differentiation such as thermal Model name LR56001 National Semiconductor has taken a unique foldback, interface to sensors or dimmer Output channels 3 approach to solving this issue with its new range adjustability. The LM3450 can be Core: 5.0 V ± 0.5 LM3450 LED driver that integrates hold implemented in either single stage or two Operating voltage I/O: 3.3 V ± 0.3 / circuitry to dynamically adjust the current stage configurations. 5.0 V ± 0.5 Consumption through the phase dimmer. The dynamic hold TYP. 12 mA circuitry, coupled with a programmable, current Operating -40 °C to 85 °C A typical application temperature circuit using the LM3450 The LR56001 LED controller can independently control up to three types of LED lights. This allows the user to choose among three types of ceiling lights—cool white, warm white and night light—with each at the desired level of brightness. That allows the user to change the color emitted, from a warm red color to a cool light blue color. Further, the built-in chopper circuit prevents power loss even when the forward voltage of the three types of LED differs.

TI Introduces Allegro MicroSystems LED Driver from New LED Lighting Introduces High Supertex Delivers Controller with Power Performance Fault Superior Current Factor Correction Tolerant LED Driver Accuracy with

Texas Instruments Incorporated introduced a Allegro MicroSystems, Inc. introduces a new Integrated MOSFET new single-stage LED lighting pulse width multi-output white LED driver for LCD Supertex, a recognized leader in high voltage modulation (PWM) controller. The TRIAC- backlighting in consumer and industrial analog and mixed signal integrated circuits dimmable solution regulates LED current and displays. Allegro’s new A8515 device has (ICs), introduced HV9967, an open loop, also achieves near unity power factor. The advanced protection features to provide average-mode current control LED driver IC reference design can achieve 85 percent optimized viewing. It integrates a current- that operates in a constant off-time mode. efficiency, which enables high-density, small mode boost converter with internal power The IC includes a 60V, 0.8 ohm MOSFET that form factor designs. The TPS92210 is switch and two current sinks. can be used as a stand-alone buck converter, designed for general lighting applications, or connected as a source driver output for such as commercial and residential recessed, driving an external MOSFET, such as troffer, light bulb replacement, architectural Supertex DN2450, to operate at offline AC line and display lighting. voltages.

Key features and benefits of the TPS92210: • TPS92210 features flexible operation modes such as peak primary current, constant on-time and frequency modulation. The constant on-time mode provides single-stage power factor The new Allegro A8515GLPTR-T is ideal for correction for improved efficiency. driving long LED strings • TPS92210’s cascoded MOSFET configuration results in 10 percent lower The boost converter can drive up to 24 LEDs switching losses with fast and easy at 120 mA. The two LED current sinks can Typical application circuit using the Supertex high-voltage start-up compared to also be paralleled together to achieve LED HV9967 driver IC competitive devices. currents up to 240 mA. This new device can • Continuous linear TRIAC dimming provides operate from a single power supply from 5 V Features: flicker-free, uniform control. to 40 V. The low 720 mV regulation voltage on • 3% accurate LED current • Multiple protection features, such as over LED current sources reduces power loss and • Integrated 60V 0.8Ω MOSFET voltage protection without optocouplers, improves efficiency. A comprehensive fault • Small outline MSOP-8 package thermal shutdown and advanced over table is included in the datasheet to describe • Low sensitivity to external component current, safely shut down the system if fault the leading-edge performance and protection variation conditions exist. features of the A8515. It also integrates a • Cascode connection with a 500V depletion- • Programmable fault response, full driver for an (optional) external input mode shutdown and shutdown restart provide disconnect switch. • MOSFET added flexibility for fault response. • Single resistor LED current setting The A8515GLPTR-T is available in an • Fixed off-time control Availability and pricing: eTSSOP-16 (LP) exposed pad package for • PWM dimming input The TPS92210 is available now in an 8-pin advanced thermal performance. • Output short circuit protection with skip SOIC package and is priced at $0.70 in mode quantities of 1,000. • Over-temperature protection

Applications: • DC/DC or AC/DC LED driver applications • RGB backlighting of flat panel displays • General purpose constant current source • Signage and decorative LED lighting • Chargers

The HV9967 features a proprietary control method that achieves fast, accurate LED current control through sensing only the switch current. The IC delivers LED current Functional diagram using TI’s new TPS92210 LED driver

accuracy of +/-3% without sensitivity to Features: external component variation. It utilizes • 19 inch rack mounted driver system – 1U average-mode current control, which doesn’t • Up to 672W output power produce a peak-to-average error, and • 384 LEDs across 24 Independent Channels therefore greatly improves LED current • Patented Dynamic Power Control and Pulse accuracy and line and load regulation without Amplitude Modulation requiring loop compensation or direct current • Backlit 16x2 LCD display menu system sensing. The HV9967 also includes internal • 100mA to 1A LED forward current per over-temperature and short circuit protection, Channel in 50mA steps and a PWM dimming input. • 8-bit master channel current resolution to TDK-Lambda’s ZPSA100 series power supplies are compact with up to 90% efficiency prove up to 4 billion colors in 3 Channels “With its unique current control method, • Wide output DC voltage range (1V to 48V) HV9967 offers solid-state lighting designers TDK-Lambda’s ZPSA100 series is approved • DMX or RDM protocol support the benefits of high current accuracy and to national and international safety approvals, • Multiple channel bonding to create high consistency for extended LED lifetimes,” including IEC/EN/UL/CSA60950-1 (edition 2) current outputs >6A states Hernan DeGuzman, Vice President of meets conducted and radiated EMC • 8 individual temperature measurement Marketing for Supertex. “This IC is quite requirements of EN55022-B and FCC Class B sensor inputs for dynamic lighting fixture simple to use, and its accuracy is virtually (without additional filtering or components) protection insensitive to the tolerances of external and meets EN61000-4 immunity • Configures as 8 outputs of 3 channels or 6 passive components in the application specifications for greater reliability. All models outputs of 4 channels circuit.” in the ZPSA100 series carry the CE mark, • 672W solution can drive up to 1000mA per according to the LV Directive, and come with channel; either 12 channels @ 48VDC or 24 The HV9967 is available in an 8-lead MSOP a two-year warranty. channels @ 24VDC. package. The part is Green and RoHS • Real Time LED current & voltage monitoring compliant. Samples are available from stock. • Over 81,000 internal program scene options Lead-time for production quantities is 4-6 IST Launches iDrive® • DMX Master/Slave options weeks ARO. Pricing is US$.80 each for the • Linear & Gamma corrected dimming HV9967MG-G in 1K quantities. Force™ - World’s selected on each channel First DSP Enabled, The iDrive® Force 24™ packs a punch with a 100W Low Profile 24-Channel LED 672W output across 24 channels in a small PCB-mountable 19”,1U package. It was surprising to find that Driver alternative products available today are twice Power Supplies from The latest addition to IST’s portfolio of the size, or offer only half the output power. world-wide patented LED driver technology is The channels are bondable, allowing multiple TDK-Lambda the iDrive® Force 24™, the world’s first DSP channels to be wired together to deliver a Power supply expert TDK-Lambda UK has enabled, 24-channel LED driver, which is a higher amp output. The Force 24™ offers 8 upped the output power of its ZPSA series of multiple channel solution for 19” rack- bit resolution as standard but provides up to compact PCB-mountable AC-DC power mounted server cabinets. Designed 16 bits with a further 256 step master supplies with the introduction of a 100W specifically with the entertainment and dimming channel and is fully DMX512A and model. The new single-output ZPSA100 architectural lighting industries in mind, the ANSI E1.20-2006 RDM compliant. accepts a wide input voltage range, has a Force 24™ is currently proving just as popular very low profile (26.6mm) and industry for white light dimming applications, due to its The exclusion of electrolytic capacitors on the standard footprint (127 x 76.2mm), making it ability to mimic tungsten dimming on DMX. LED output stages serves to prolong the life an ideal choice for applications such as LED of the driver, avoiding one of the major signage and lighting, point-of-sale equipment, reasons behind LED driver failures. In datacom, video/audio routers and test & addition, the multiple channels enable faster measurement equipment. programming of the rack-mounted drivers, which in turn reduces installation times. Accepting a wide input voltage range of 90-264Vac (47-440Hz) or 120-370Vdc, the At the core of the Force 24™ is the latest ZPSA100 series is ready for use globally with Texas Instruments 32-bit Digital Signal no further configuration or input selection. Its Processor with high performance integrated industry standard footprint makes it an ideal peripherals designed for real-time control choice as a drop-in replacement for existing applications. The eco-DSP™ platform IST’s iDrive® Force 24™ packs a punch with a supplies, while its low profile means that it can 672W output across 24 channels in a small enables the installer to program each channel be installed in the most compact of 19”,1U package for LED currents from 100mA up to 1A per applications. channel in 50mA steps and Vf voltages from 1V up to 48V.

Matt Fitzpatrick at IST enthused: “The iDrive® The DecaLED® Touch Panel DMX 4 is ideal placement of LEDs in narrow or recessed Force 24™ is the first LED driver to utilize our for small stand-alone installations where 12V spaces, as well as in diverse LED new eco-DSP™ platform so users will be able or 24V DC LED products are used, such as configurations never considered before. This to benefit from a highly robust and energy DecaLED® Flex RGB, DecaLED® Flex RGB evolution is not without difficulties because it efficient driver. The eco-DSP™ platform HD and DecaLED® Cove Flex RGB. It is requires the employment of new technologies enables common anode connected LED therefore an interesting product for i.e. interior while guaranteeing high efficiency and fixtures to be used as well as allowing more designers, stand builders and restaurants, superior performances. than one channel to be bonded together to bars and hotel businesses. get forward currents up to 8A. It is the most Round Reflector Products: the flexible LED driver platform I have seen • KCLP17CR (Metallized Version), 17.55 mm since I joined the LED industry 10 years ago”. Kathod Showcased Diam; 10.71 mm Height, Narrow Beam • KCLP20CR (Metallized Version), 20.45 mm The next highly anticipated addition to the Series of Improved Diam; 10.71 mm Height, Narrow Beam Force 24™ family will be an incandescent light and New Optics • KCLP17ST (Embossed Version), 17.55 mm bulb dimming version, UltraDim, which is Diam; 10.71 mm Height, Medium Beam capable of removing visible DMX steps for LED Lighting at • KCLP20ST (Embossed Version), 20.45 mm dynamically in real-time. Diam; 10.71 mm Height, Medium Beam electronica 2010 At electronica, Khatod showed up with an Common Features: Introduction DecaLED extended portfolio of LED optics: ZETALENS, • High efficiency realized in round and square shapes; • Available in 2 different beams Touch Panel DMX 4 STRIPLENS, specific for a new LED mounting • Ø 17mm and Ø 20mm Standard The DecaLED® Touch Panel DMX 4 is a concept; TRIPLE and QUAD MINI LENS; • Typical applications: Portable lighting, compact LED controller with DMX512 and ROUND REFLECTORS; and the DARK LENS, Lamps, Architectural lighting PWM outputs. The stylish design in glossy a first-of-its-kind anti-glare reflector. • Most applications where a compact light black polycarbonate can easily be built into a source is required wall socket. The panel has no buttons but it is ZETALENS - The continuous evolution of pressure sensitive. The device has a user LED technology has resulted in a reduction of NEW MULTI LENSES - Khatod unveils the friendly design. LED dimensions and size, and an increase in most comprehensive range of MULTI LENSES luminous output. Zetalens, realized in NJC specific for multichip MINI POWER LEDs. technology, allows for the housing of 7 LEDs Dedicated to the most demanding and is available in narrow, medium and wide applications in Lighting Design, the Series Beams. Its shape and dimensions, available in include one of the most expected lenses on 4 different configurations, offers designers as the market PL350ANK TRIPLE LENS, a well as the final user the freedom to choose 50.02mm Diameter Triple Lens, specific for among 12 models. The result is a very diverse Mini LED applications requiring this size. lens family that can be used in a variety of applications. MINI LENSES is dedicated to the new generation of MINI POWER LEDs. The MINI The DecaLED® Touch Panel DMX 4 LED ROUND REFLECTORS - The request of high LENSES, created with the proven NJC controller offers both DMX512 and PWM outputs efficiency in Lighting along with the upmost technology, are superior, technologically necessity of energy conservation, have made advanced products that meet and exceed the This panel includes the following features: the Power LED applications an ever- most demanding requirements of the market. • Static color, configured by means of a increasing requirement in the lighting Industry. Mini Single Lenses are the new generation of handy swivel function. 4 color settings can Many of these new applications require optics for superior lensing for your projects. be stored in memory. Kathod’s well • Choose from 10 preset color loops, for established and which the transition speed and intensity can new products at be adjusted. 4 preferences can be stored. electronica 2010 • Usable as DMX controller. (from top/left to • When using an external 12V or 24V DC bottom/right): Round Reflector - power supply, for example, led strips metallized verions, directly connected to the PWM output. Round Reflectors - • Dimming of your choice (0 ~ 4 seconds) for embossed versions, on and off. the Dark Lens, Triple • Use up to 2A per channel, in total suited for Minilens, Zetalens - round, Zetalens - a maximum of 6A. square, and Colour • Visible indication of the current RGB color Mixing Lenses on the front of the panel.

The MMCS6 product MAZeT New Products family offers accurate measurement options Highlighting MMCS6 with seven spectral characteristics in the Multiple-Color-Sensor range of 380-780 nm With the principle of a multiple color sensor, MAZeT is pursuing a strategy that bridges the gap between the three-range sensors and spectral measurement devices for sensor applications. The integrated TIAM4 multiple color sensors module, contains the entire sensor electronics on-chip, in addition to the spectral operating detector. The new MDDC 4-channel sensor signal amplifier for sensors with current output is suitable for fast applications in conjunction with detectors and arrays, such as In-Line (Color) Measurement The spectral characteristics of the MMCS Simulation Tool for Color Measurement and control in automated processes. Finally, sensors are arranged in such a way that their Tasks and Regulation of RGBxx LEDs MAZeT also offers a tool for simulating border areas overlap. It follows that only as - MAZeT offers a tool for simulating compact compact spectrally-selective semiconductor few gaps as possible exist in the visible spectrally-selective semiconductor sensors sensors for accurate in-line measurements. spectrum. Misleading interpretation of the for accurate in-line measurements. The colors is thus minimized and the system is simulated with the tool starting with JENCOLOR - Multiple Color Sensors for measurement accuracy increased. The the feasibility study and is optimized Accurate and Fast In-Line Color Measurement sensor operates largely independent of the according to the requirements. Both the The multiple color sensor bridges the gap quality of the light sources. Through the selection of the correct sensor and the between the three-range sensors and spectral approximation of the measured color optimum composition of filters and lighting are spectral measurement devices for sensor using MMCS sensors, color differences to achieved in advance with the simulation applications. which the human eye does not respond can software to enable the best possible quality be determined even there. for the actual measurement. The new MMCS6 product family is based on the proven technologies of the compact TIAM4 Multiple Color Sensors On-Chip - A and price-to-performance ratio-optimized new member of the multiple color sensors is Industry’s First semiconductor sensors with integrated the so-called integrated TIAM4 module. In interference filters. With the MMCS6, a addition to the spectral operating detector, it Multidirectional Mini color measurement with seven spectral contains the entire sensor electronics on-chip. Blower characteristics in the range of 380 to 780 The photocurrents of the detector are nm can be taken on the basis of spectral converted into voltages and are available via Providing a unique solution for customized estimation. S & H on a MUX on the output side as an air-flow applications, JARO’s new JRB2235 analog voltage signal for digital conversion. series rotates at 8500 RPM’s and produces a The evaluation of a color in this sensor is The TIA-based amplifier is individually powerful 1.2 CFM of super-cooled air (with a based not on the colorimetric but on the programmable in transimpedance over eight static pressure of 0.122” of H2O). Operating radiometric level. The initial result is not the levels and is characterized by a very good voltage is 4.0 V to 5.5 VDC. The availability of chromaticity coordinate but the spectrum linearity in the amplifier stages and by low single or dual unit configurations provides of a color, which can be then used to noise. customers with the unique ability to select the calculate the chromaticity coordinate. The precise direction(s) of airflow, making this the advantages of such measurements lie in the The new Multi-Channel Amplifier IC, MDDC first multidirectional mini blower in the Thermal much higher information density in terms of 4-channel sensor signal amplifier, for sensors Cooling Industry. color measurement. with current output converts small input currents quickly and across a high bandwidth The MMCS6 sensor confers the advantage and dynamic range and digitizes them on chip that the recognition and measurement of via a transimpedance amplifier. metamerism effects can be filtered out, Transimpedance amplifiers are preferred in which cannot be done with RGB or XYZ industrial measurement technology for their sensors. Metamerism in the optical sense rapid and cyclic conversion and amplification means various spectra that for a defined type of the very small currents used in of light produce the same impression on the optoelectronic sensors. The ASIC is suitable human eye. for fast applications in conjunction with detectors and arrays, such as In-Line (Color) JARO’s new JRB2235 series mini blowers are Measurement and control in automated one of the most compact blowers on the processes, such as printing and analysis. market

These new subminiature blowers are aluminum reflectors. The thermal-curing peak, and centroid wavelengths; color conveniently designed for small solder bath resistant screen printing lacquer temperature and rendering properties; and applications (22x26x35 mm). Applications FP 2410-1020 can be used on top of either purity. To capture and organize data, DLL include: LEDs, pocket projectors, MID/UMPC/ white or green photoimageable solder resists. drivers are available to connect the Smartbooks, CCTV, GPS, fuel cells, portable spectrometers to proprietary QA, calibration gas/particulate detectors, portable plasma A maximum light yield plus a reliable and production software. generators, ventilation and defrosting. protection is ensured when selective-coating According to Jaro Thermal’s VP, Dennis Eisen, with white-opaque conformal coatings such With a spectral range of 305-930 nm, the “The new blowers lead the industry in as ELPEGUARD® SL 1397: All LEDs are CDS-5400 is well suited for production line customizable, aimable air-flow products, while spared during coating while dark components testing of high brightness LEDs. With a 2ms providing compact design, long life & high are covered, thus increasing the light yield integration time, the CDS-5400 delivers the quality.” (remission) distinctively. The ELPEGUARD® SL high speed required by these environments. 1397 is characterized by extremely high For more high precision applications including remission values along with a high light and fixed quantity UV and quantum efficiency Newl Products heat stability. measurement, the CDS-9800 has a wide dynamic range and four models covering the for Coating LED A striking contrast with the base material plus spectral range of 240-1100 nm. With low stray Assembled PCBs reliable protection can be achieved by the light, the highly accurate CDS-9800 is black-opaque, mat conformal coating intended for demanding R&D environments To a growing extent, PCBs are assembled ELPEGUARD® SL 1347. With this product, it is where precision is critical and a wide variety with LEDs and are thus partially visible when possible to selective-coat your assembled of devices need to be tested. used in illuminants. In choosing your solder PCBs in black which are usually coated with resist or conformal coating, you will therefore green solder resist, in a way that a striking have to consider optical requirements, too. contrast of the LEDs with the non-reflecting Essemtec base material is produced. This is of particular advantage in display applications such as Introduces New panels, signaling lights etc. LED Manufacturing Labsphere Launches and Assembly High Speed LED Technologies Product Essemtec announced that it highlighted Characterization Pantera-XV at the LED EXPO, that took place in New Delhi, India, from December 17-19, Spectrometers 2010. Pantera-XV is a highly versatile,

An optical adaptation to aluminum reflectors Designed for a full range of LED Swiss-quality pick-and-place, suitable for can been implemented by coating with the characterization measurements, Labsphere LED, standard SMD placement and silver-grey 2-pack screen printing lacquer FP (www.labsphere.com) has introduced the dispensing. High-quality dispensing valves 2410-1020 CDS-5400 and CDS-9800 High Speed LED from Vermes were also featured. Spectrometers. Both models offer reliability, For optimizing the radiation characteristics of speed and accuracy with a choice of spectral LEDs, white solder resists are particularly range to suit specification application needs. well-suited, such as the temperature-stable solder resist ELPEMER® SD 2491 SM-TSW- R2. This product stands for the new generation of purely white, opaque photoimageable solder resists which have maintained the high remission values as well as the outstanding thermal stability of their predecessor ELPEMER® SD 2491 SM-TSW- R1 and which, on top of this, can be processed more securely within immersion tin (Sn) and immersion gold (ENIG) methods. Labsphere’s CDS-5400 and -9800 deliver spectroradiometric and photometric An optical adaptation to aluminum reflectors measurement for solid state lighting. can been implemented by coating with the silver-grey 2-pack screen printing lacquer FP The CDS spectrometers, when integrated into 2410-1020. This product with the typical Labsphere’s systems, measure critical aluminum look is recommended for LED spectral characteristics of LEDs including flux; Pantera-XV from Essemtec is a new affordable assembled boards in illuminants provided with intensity; chromaticity coordinates; dominant assembly and dispensing system

Pantera-XV from Essemtec is an affordable, Swiss-quality assembly and dispensing system, designed for small and medium size series production. It can accurately pick and place SMD components and LEDs. It features fast optical component alignment systems for components from 0201 up to 50x50 mm. Pantera-XV and also can dispense glue, conductive glue or solder paste.

Pantera-XV is a highly flexible system that can be changed from one production to another The new Peter Wolters slurry reaches the An ultra-large 10-inch C-plane epi-ready without standstill. Feeders can be exchanged surface roughness endpoint in half the time sapphire substrate from Monocrystal is now while the machine is producing and are compared to the standard colloidal silica slurry available recognized automatically. Furthermore, This quality slurry product is completely mixed “We were ahead of competition with our best programming for placement and dispensing and tested by the PETER WOLTERS in-house in class 8-inch sapphire substrates for LED can be done on an external PC. Pantera-XV professional team of scientists and engineers and RFIC applications. Now, the introduction also features “Virtual View,” which ensures the to maintain the highest levels of consistency of innovative 10-inch LED sapphire substrates quality from the first PCB of a series. and quality. The premixed slurry is shipped in clearly demonstrates that Monocrystal is well a concentrated form, which can be easily positioned to support the growing market Other highlights on Essemtec’s booth include thinned to the proper point of use consistency demands and expands LED industry the micro jet dispensing valves from Vermes. by adding DI water. Handling and storage of prospects. This further strengthens Known for their accuracy, speed and this custom slurry does not require any Monocrystal position of technology and flexibility, these valves can be cleaned easily exceptional processes or procedures beyond industry leader,” said Oleg Kachalov, CEO of and, therefore, are suited for different what is typical to common colloidal silica. the company. dispensing tasks. The repeatability and reliability makes Vermes dispensing valves the This new polishing slurry demonstrates again Today, sapphire substrates are used for more first choice for dispensing of the LED lens. that PETER WOLTERS has become well than 90% of GaN LED chips produced by the established as a market-leader for spares and industry, including high-brightness devices accessory products which have undergone used for LED lighting products. Compared Advanced LED years of laboratory and field testing to ensure with conventional incandescent lamps, LED they meet the most exacting standards, with consumes up to 90% less energy, and its life C-Plane Sapphire proven consistent and dependable results. spans 50 times longer. Due to their unique Polishing Slurry features, LEDs also have become increasingly adopted in other applications, such as mobile Enable 50% reduced Monocrystal devices, displays, traffic lights, car lighting Polishing Time Introduces 10-inch and interiors. PETER WOLTERS is introducing to the LED Sapphire Substrate to market a new polishing slurry that has Breault Research demonstrated a 50% reduction in the time Expand LED Industry Releases New required to complete final polishing for flip Prospects chip or through substrate LED’s. This Version of ASAP® development utilizes a combination of Monocrystal, a leading manufacturer of chemical and abrasive technologies to electronic materials for LED and solar Breault Research Organization (BRO) has decrease the cost of ownership or the industries, announced the availability of the released a new version of the company’s manufacturing cost of the LED when company’s innovative ultra-large 10-inch Advanced Systems Analysis Program manufactured on C-plane sapphire. “As C-plane epi-ready sapphire substrate. (ASAP®). The ASAP 2010 V1R1 release demonstrated by our testing, the time includes new features and enhancements to required to achieve a comparable final surface The LED industry continues shifting to larger the most sophisticated program for virtual finish has been reduced by half in substrates diameter substrates as it strives to achieve prototyping of optical systems and devices. of identical incoming quality”, said David higher cost savings and to increase production New features and enhancements in ASAP Suica, President of Peter Wolters of America, throughput of quality LED chips to bring LED 2010 V1R1 include additional library the PETER WOLTERS Competence Center for lighting closer to its widespread use. resources, enhancements to the BRO Sapphire Polishing. Digitizer and REMOTE features, biaxial Driven by its strong commitment to birefringence modeling, support for the import The quality and clarity of the final polished technology innovation for sustainability, and export of new photometric data formats, surface is comparable with the utilization of Monocrystal continues developing next updated CAD interoperability, as well as other colloidal silica, which is commonly utilized in generation large-diameter sapphire wafer software repairs and enhancements. the final polishing step. technology.

Quantum Dots are not Dots Researchers from the Quantum Photonics Group at DTU Fotonik in collaboration with the Niels Bohr Institute, University of Copenhagen surprise the scientific world with the discovery that light emission from solid-state photon Screenshots of the enhanced opportunities; emitters, the so-called quantum dots, is Light Source Library Additions, Photometric fundamentally different than hitherto believed. Data Transfer, Scatter Model Library Additions, The new insight may find important and ASAP/CATIA Interoperability applications as a way to improve efficiency of ASAP 2010 V1R1 Highlights: quantum information devices. Their findings • Light Source Library Additions - Over 40 were published on December 19th 2010 in the new models, including Luxeon, OSRAM, prestigious journal Nature Physics. Philips, and Bridgelux sources. Quantum dots are solid-state “artificial atoms” • Scatter Model Library Additions - New Today it is possible to fabricate and tailor that are made up of thousands of atoms (yellow spheres) embedded in a semiconductor (blue Alanod MIRO, MoldTech, Tenibac, and highly efficient light sources that emit a single spheres). Despite this complexity, the photon other material models. photon at a time, which constitutes the emission properties of quantum dots were • Enhanced BRO Digitizer - Automatically find fundamental unit of light. Such emitters are hitherto believed to be like traditional atoms, the data curve(s) on a graph using the referred to as quantum dots and consist of where a point-emitter description is sufficient. enhanced BRO Digitizer. thousands of atoms. Despite the expectations Due to their mesoscopic dimensions, however, the point-emitter description is revealed to • Enhanced REMOTE - Better file handling, reflected in this terminology, quantum dots break down by comparing photon emission access from scripting, and new tools for cannot be described as point sources of light, from quantum dots with opposite orientations summing and averaging results. which leads to the surprising conclusion: relative to a metallic mirror • Photometric Data Transfer - Import and quantum dots are not dots! export files in the EULUMDAT and IES demonstrates that the excitation of plasmons LM-63-02 photometric data formats. This new insight was realized by can be even more efficient than previously • ASAP / CATIA Interoperability - Open native experimentally recording photon emission thought. Thus the fact that quantum dots are files from the CATIA® V5 r13 through r20 from quantum dots positioned close to a extended over areas much larger than atomic releases (optional add-on). metallic mirror. Point sources of light have the dimensions implies that they can interact • Biaxial Birefringence - Model materials with same properties whether or not they are more efficiently with plasmons. biaxial birefringent properties such as flipped upside down, and this was expected thin-film coatings. to be the case for quantum dots as well. The work may pave the way for new • Other Enhancements - Dozens of other However, this fundamental symmetry was nanophotonic devices that exploit the spatial command enhancements and customer- found to be violated in the experiments at extent of quantum dots as a novel resource. requested changes. DTU where a very pronounced dependence The new effect is expected to be important of the photon emission on the orientation of also in other research areas than plasmonics, According to BRO’s VP of Software the quantum dots was observed. including photonic crystals, cavity quantum Development, Dr. Kyle Ferrio, “The latest electrodynamics, and light harvesting. release of ASAP delivers customer-requested The experimental findings are in excellent tools to enhance productivity and reach agreement with a new theory of light-matter The research group behind the discovery: applications beyond any previously available interaction developed by DTU-researchers in The research was conducted in the Quantum commercial software. These are exciting collaboration with Anders S. Sørensen from Photonics Group at DTU Fotonik, Technical times for optical engineers and scientists at the Niels Bohr Institute. The theory takes the University of Denmark by a research team the forefront of product design and spatial extent of quantum dots into account. consisting of postdocs Mads Lykke Andersen innovation, and we are excited to support and Søren Stobbe and associate professor their success with this new release.” At the metal mirror surface, highly confined and group leader Peter Lodahl in collaboration optical surface modes exist; the so-called with associate professor Anders S. Sørensen plasmons. Plasmonics is a very active and from the Niels Bohr Institute at the University promising research field, and the strong of Copenhagen. confinement of photons, available in plasmonics, may have applications for quantum information science or solar energy harvesting. The strong confinement of plasmons also implies that photon emission from quantum dots can be strongly altered, and that quantum dots can excite plasmons with very large probability. The present work

The tiny controllers not only measure the intensity of the light falling on the workspace from the LEDs, but also identify how much light can come from different fixtures while separately measuring any ambient light coming in from the windows or spillover light from neighboring work areas. So if the sunlight from the window is sufficient to meet the user’s needs for lighting, the overhead lights can dim or switch off altogether, and then are immediately reactivated if the sunlight decreases because clouds roll in. The color balance of the light can ILD 4035 and ILD 4001 also be adjusted by varying the intensity of individual LED lamps of Step-down LED drivers for 1W and 3W+ LEDs different colors installed in the overhead fixtures.

The new ILD 4035 and ILD 4001 from Infineon Technologies In tests of the system so far, the researchers found that it reduced the are part of a new LED driver family dedicated to general lighting applications. energy used for lighting by 65 to 90 percent — and that’s on top of the already-high energy efficiency of LEDs compared to incandescent 40V input voltage 350mA LED current (ILD 4035) lights and compact fluorescents. And while LED lights are the most Up to 5A LED current with external MOSFET (ILD 4001) efficient, the control system could be used with other light sources as Overvoltage, overcurrent and thermal protection Small SC-74 package well, including incandescent or dimmable fluorescents.

To learn more about the LED driver portfolio for General Lighting, please visit Preliminary results of the ongoing research, which is funded by the Media [ www.infineon.com/lowcostleddrivers ] Lab, were published this summer in the Proceedings of the SPIE, in a paper co-authored by Aldrich, Paradiso and visiting student Nan Zhao.

While the system works in its present form, it needs to ramp the MIT Study: Energy Savings lighting up and down to calibrate the sensor whenever it is moved, and this can produce a distracting but brief sequence of light and dark. through User-Controlled Lighting Aldrich is now working on a system that incorporates invisible infrared Systems (IR) LEDs in the light fixtures and IR sensors in the controllers. In this way, when the relationship between the IR and visible light is properly These days, in newer buildings it’s often hard to even find a plain calibrated, the adjustment of light levels and the system calibration can old-fashioned light switch. Often, the only controls are automatic be done invisibly and without unnecessary distractions. The group is motion-detector switches that turn off lights when people have left a also using cameras to measure reflected light across illuminated areas room — or when they sit too still — or else daunting control panels and is studying ways of using gestures for lighting control. with arrays of sliders and buttons. But some researchers at the MIT Media Lab are aiming to put the controls back in people’s hands, in a In addition, Aldrich plans to do further testing on user reactions to the way that provides sophisticated and continuous control and could system in order to optimize the control systems to match user slash lighting bills by more than half. preferences. For example, would it be more effective to let each user control the lighting for his or her own space, or to allow a single control for an area or a work group? And is it better to have the controls in fixed locations, or have portable devices that control lights as a user moves around in the building? “We want to see how users will interact with it, to see if we can really realize these energy savings,” Aldrich says.

Jeffrey Cassis, the CEO of Philips Color Kinetics says that the team doing this work “is world-class — they are working on a hard problem and a quality, cost-effective solution has great potential.” He says that it is important to use a systems approach, as this team is doing, looking at the whole lighting system rather than just individual Visiting student Nan Zhao works in the test setup at the Media Lab. The components. But he adds that the cost of the finished system, as well currently used device that incorporates sensors and controls is not much as how easily it can be used to retrofit existing lighting systems, will be bigger than a credit card (photo courtesy of Matt Aldrich). crucial factors in determining its adoption.

The experimental control devices being tested by research associate And Bob Karlicek, director of the Smart Lighting Engineering Research Matthew Aldrich are about the size of a business card, and thin Center at Rensselaer Polytechnic Institute, says such systems offer the enough to slip in a pocket. They monitor the light actually falling on the “possibility of much higher energy saving than can be obtained user’s work space, and contain light sensors as well as controls to through LED lighting without intelligent control systems.” "But," he adjust both the intensity and the color balance of the light. In the test adds, “there are still significant technical barriers that need to be setup, this information is used to control an array of LED light fixtures, overcome on at least three fronts: higher efficiency color adjustable the most energy-efficient kind of lighting now available that can be LED lighting, new types of lighting sensors that can be used to control easily adjusted to any level of intensity. lighting systems, and new ways for people to interface with adaptive lighting control systems for maximum productivity and comfort.”

EVENTS OLED-SUMMIT MEETING 24

The Display Industry Drives OLED Technology

Alan Mills reports from the Intertech-Pira OLED-Summit meeting, where remarkable progress in OLED display technology was seen and shows how it influences the OLED market for general lighting.

Today’s annual worldwide lighting Although small OLED displays are those of LCD models with roadmap market is about $100 billion with increasing their market penetration, forecasts indicating a reduction to 3x the US share being about 20%, progress in the OLED TV market in 2013, 1.5x in 2015 and a crossover and the European share close will be slower. Prototype OLED TVs, or 1.0x in 2017. Most of these cost to 40%. Light Emitting Diodes such as the LG 31-inch AMOLED and improvements are anticipated from (LEDs) account for less than Mitsubishi 155-inch PMOLED models, lower material costs and higher 1% of the lighting market with have recently been demonstrated, manufacturing yields. However, the organic light emitting diode or but high volume manufacturing achievement of these goals may OLED display sales being in the lines are still only in the planning be difficult; since the ideal process same value range. However, most stages. Several performance factors materials and process technologies OLED devices are small displays such as the electron mobility of the have yet to be defined for the with the estimate for world TFT backplanes and their voltage production of low cost large panel TFT sales being about $650 million stability, plus image sticking, blue based OLEDs. Additionally, today’s in 2010. This value represents a emitter lifetimes, scalability, preferred OLED TV panels use two layers of 30% growth over the previous threshold voltages of less than 3.5V, glass for support and encapsulation. year, and a continuing rapid comparative cost, and sagging Therefore, the development of lower growth for organic light emitting shadow mask alignment issues for cost designs with one glass sheet and diode (OLED) technology for large displays and TVs will have to plastic encapsulation is a must achieve the foreseeable future. The US be solved for Gen-6 production lines factor. Department of Energy actively before widespread market acceptance supports both OLED and LED of OLED TVs becomes more realistic. Small OLED Displays technology development, with Companies such as LG, Motorola, allocations in 2010 of about $60 Jueng-Gil Lee from LG Display and Nokia and Samsung have previously and $90 million respectively. This others have reported that typical blue marketed cellphones with OLED OLED investment is equivalent to emitter materials only have lifetimes displays, but Samsung Mobile Displays almost 10% of annual worldwide in the 5,000-10,000 hour range, Division had allocated significant sales, where the vast majority of whereas the green and red emitter funding for OLED displays in order these sales are for portable small lives to 70% brightness are at least in to target increased penetration of display applications including cell the 70,000 to 100,000 hour range. In the cellphone market. This resulted phones, MR3s, or cameras. 2009 OLED TV costs were about 10x in Samsung OLEDs accounting for about 95% of the 2010 small display Figure 1: market value. A majority of Samsung The Samsung Galaxy Series is sales have been used internally just one example for cellphones, even though OLED whre small OLED displays are believed to be double the displays are used cost of LED illuminated equivalents. Jennifer Colegrove, from Display Search stated at the Intertech-Pira OLED-Summit meeting that the Samsung Galaxy Series (see Figure 1) displays have a 2x VGA resolution with 235dpi and 800x400 pixels. For comparison, the Apple iPhone-4 offers 326dpi with 960x720 pixels. However, OLED displays could

not be considered at this time for the for two-inch displays, from a low 15 represent significant penetration into Apple phones because there is not candela per A (cd/A) performance in the well-established worldwide LCD enough capacity worldwide to supply 2007 to 20 cd/A in 2009, 24 cd/A in panel display market that passed the their present shipment levels. This 2010, and are forecast to achieve $100 billion mark in 2008. However, situation could change in the future 30 cd/A in 2011. Consequently, the it presumes that sufficient display because up to 10 new OLED-fabs may respective power draw for a 2-inch manufacturing capacity would be be built in the next two years. display should drop from about available. With estimates of 3 million 400 mW per display in 2009 to square kilometers of OLED devices The benefits claimed for mobile 252 mW in 2012, thus allowing a better being sold in 2012, an annual market active matrix (AM) OLED displays are competitive position for OLEDs against for about 300,000 tons of OLED thinner displays (compared to AM LED backlit displays. However, this is a related materials would be created. LCDs), less weight, lower power use, moving target since the luminous flux , improved definition or visibility, good lm/W and lm/$ outputs of LEDs are In addition to their small display touch screen capability, no back also still improving, with 150-180 lm/W production and R&D at Samsung lighting units required and eventually outputs from one Amp LEDs being Displays, Ho Kyoon Chung, reported lower manufacturing costs. However, expected by 2014. to the Intertech meeting that their near barring rapid process technology term large-format work is focused on breakthroughs, significant challenges Comparative display resolution has TVs and large flexible displays. After still exist including; display cost, a lack been reported as 350 ppi for LEDs, TVs, their R&D will lead the company of high volume manufacturing lines 330 ppi for OLEDs, and 240 ppi and into large flexible screen displays and (excepting Samsung), the lifetimes of higher for the iPad, but pixel densities OLED wallpaper for room or space blue emitters (organic small-molecule continue to improve. Increased current lighting. It is interesting to note that in or polymer) and power requirements. densities are desirable for brighter a parallel situation to the LED of about Today, there is a reduced demand OLED displays, but they increase the 15 years ago, commercial small display for the more mature passive matrix operating temperatures and increases applications technology is supporting PMOLEDs. Hence, AMOLEDs with as small as 5ºC can lead to shorter much of the developing lighting amorphous silicon thin film transistor OLED material and display lifetimes. technology for OLEDs. (a-Si TFT) backplanes have become For future displays, Jong Huyk Lee Figure 2: the preferred technology. However, from Samsung’s OLED Technology The "Tree Lamp", designed by Ingo the relative cost of the silicon team has stated that the company is Maurer 2008, and TFT backplanes may be a near focusing on their LITI (Laser induced made by Osram is term impediment to a successful thermal imaging) process, which needs an early example competition with AM LEDs and additional process development, but for OLED lighting, LCDs, therefore oxide TFTs are being it will have no ppi limits. Paper-thin expressing more of an art form than evaluated for lower manufactured cost displays of under 0.5 mm are another a solution to a AMOLED alternatives. Additionally, goal and could open up new OLED lighting need low temperature processed TFT back markets such as credit card, driver’s planes for future large, flexible OLED license, ID card and e-passport uses. displays are one of the challenges to low cost manufacture. As OLED technology continues to advance, the outlook for touch screen At the Intertech-Pira OLED meeting, a OLED displays appears to be very report from the Samsung Mobile promising and market forecasts for Display Division indicated that it is these displays range between $6 and currently focusing on small to medium $12 billion for 2018, with Samsung sized AMOLED displays for the 2010 to promoting the more aggressive 2012 near term and noted the forecast. The $6 billion estimate by advantage of not requiring a back Display Search is based on sales lighting unit. Ho Kyoon Chang of 60 million square metres of small mentioned that the company plans to displays at an average price of $100/ OLEDs for Lighting and expand into OLED TV markets and M2. However, with an estimated Large Displays ‘some unique applications’ by 2013, cellphone market of 2 billion units in Today, only a few OLED lighting followed by the ‘next big thing after 2015, and if one third of these are prototypes are being manufactured TVs’, large displays. Presuming the fitted with OLED displays, it would in small quantities and promoted technical issues are solved, a 50% represent an even larger OLED display by such companies as Acuity, GE, penetration of some markets is market of about $14 billion at $20 Osram and Philips. They are more of forecast by 2015, including an per display (without any contribution an art form than a solution to a lighting expanded use of OLED touch screen from OLED TVs and large displays). need, with the first example being technology. Display power-use This plausible scenario even exceeds the "Tree Lamp" made by Osram in efficiencies are continuing to improve the above 2018 forecasts and would 2008 (see Figure 2). This Ingo Maurer

Figure 3: blues being rated at 9000 hours with A more recent ceiling luminaire an output efficiency of 46 lm/W. As from 2010 noted earlier, short-lived blue emitters could slow the acceptance of OLED luminaires for lighting applications.

In furtherance of the flexible-sheet OLED technology, both Samsung and Sony demonstrated prototypes in 2010. Presuming success, Samsung expects this market to achieve $100 million in sales by 2012, $2.4 billion in 2015 and $30 billion by 2020. Samsung plans to focus on large ultra thin rollable displays and OLED wallpaper for lighting Figure 4: after it has established an OLED TV New improved OLED structures market. Successful flexible display allow higher production will depend on technology luminosity, solutions to several challenges (low recently up to cost film, flexible electrodes, low 3,000 cd/m2 temperature TFT processes and display bending radii of about 1cm), but the most important challenge is the development of substrates and multi layer barriers that exclude air designed lamp, with only about 2000 from small pixel OLEDs that have and water. Samsung has reported hours to 50% luminance, produced little correlation with lm/W outputs recent progress toward these goals low intensity lighting from small for OLED lighting panels. For this with the development of a flexible 2.8 oblong panels with claimed benefits reason the US DoE no longer accepts inch AMOLED display using a low of no glare, decorative, form factor OLED pixel performance values as temperature poly silicon TFT process and art values. A prototype OLED a measure of OLED performance. A and multi layer ALD/MLD barrier films. ceiling-panel luminaire has also been roadmap milestone of 60 lm/W for MLD (molecular layer deposition) is reported (see Figure 3). Such OLED an OLED panel was the goal for 2010 a recently developed process that luminaires are expensive, but their rising to 100 lm/W in 2015 at a 10,000 alternately delivers trimethyl aluminium sales presently have insignificant value lumens per m2 luminosity rating. Triplet and ethylene glycol (EG) to form when compared to the general lighting spin-state OLED emitters, utilizing Alucones, inorganic/organic hybrid market and face tough competition phosphorescence, are the answer to polymers. This AMOLED can boast from the latest fluorescent lamps the higher performance since they a bending radius of < 1cm, 0.24mm and light emitting diodes (LEDs), with allow almost 100% internal quantum thickness, 240x400xRGB (166ppi) respective 80 and 110 lumen per watt efficiencies (IQEs) and also waste less resolution, 250 cd/m2 luminosity and (lm/W) efficiencies and much lower power as heat. weighed only 0.29 gramms (see costs. The 150 lm/W efficiencies Figure 5). and lower costs expected from According to Janice Mahon from LEDs in 2012 will provide even more Universal Display Corp. (UDC), their competition. However, the goals for company now offers under their OLED lighting are to convert walls, PHOLEDTM trademark, emitters with windows and ceilings into no-glare long-lived estimates to 50% output (95 light sources and to provide thin, to 500k hours), reds that produce 15- flexible and transparent large displays. 28 lm/W and greens with 60-75 lm/W. UDC also recently demonstrated an The best lumen per watt outputs for 8x8-inch white OLED panel with about OLED devices vary widely with existing 3000 cd/m2 luminosity, see Figure 4, luminaires producing about 25 lm/W that uses a 2-blue, 4-pixel (Red, Green, Figure 5: New AMOLED displays have a and rising to 40 lm/W in 2011 versions, Blue1 Blue2) arrangement for their narrow bending radius although R&D OLEDs have been P2OLEDs. However, even fairly new reported at 102 lm/W. Higher values in blue OLED emitters are not as durable, the 60 to 100 lm/W range are usually with one of the most recent UDC

Several large-OLED manufacturing techniques and organic materials systems are under testing, including:

• Small organic molecule (SM) OLED devices by deposition in an OVPD (organic vapor phase deposition) process (see Figure 6)

• Organic polymer OLED devices (POLEDs) either using polymers in solution that are spin-coated or use inkjet deposition and roll to roll transfers that combine pre- formed OLED layers and

• Mixed-material layered OLEDs that use both material types in solution. To date, the final selection of a manufacturing process has not been reported.

Fortunately, worldwide R&D continues to improve OLED luminaire luminous flux levels, lifetime performance and dollar per lumen cost. As large-OLED manufacturing technology continues to mature, the OLED industry goals of Figure 6: AIXTRONs advanced OVPD® furnace for small OLED production large display and luminaire OLED production becomes ever closer.

The Future of LED Systems is Digital

At the VDI conference, Peter Deixler, Global Senior System Architect, LED Lamps & LED Systems from Philips Eindhoven gave a comprehensive overview on „Trends in SSL Driver Electronics & Luminaire-based Controls.” Arno Grabher-Meyer from LED professional got the chance to discuss that exciting topic with him.

LED professional: One key issue of LED professional: Is this approach Revenue” lighting solution business your speech was the change from an especially favorable for SSL lighting? models will ask for secure feature analogue world to a digital world for Why or Why not? upgradability in field. driving LEDs. That approach does not sound very new, because in Peter Deixler: In a full-digital driver, the LED professional: At VDI you also industry, the term “digital power” is software has direct control of demonstrated how a digital often loosely defined with respect to everything within the lamp. This approach allows the reduction of power supplies. Sometimes the term enables rather straightforward digital driver size, especially due to higher refers merely to a switching power feature integration. Additionally, the operation frequencies, resulting in supply. microcontroller enabling these digital miniaturized magnetic. Could you please give us a short and features is already “paid for” by the What is your opinion regarding the clear definition of what a real digital power conversion. Digital light-sources integration of passive components in driver or power supply is? will offer many new possibilities for silicone? customers, such as smart office Peter Deixler: In a “Full-Digital” LED buildings with distributed daylight and Peter Deixler: Indeed, Full-Digital- Driver, the control of power converter presence sensing. For the consumer Control of the power conversion is realized by means of a micro- space, smart energy saving and enabled the use for our product controller with digital control loops. ambience creation in homes will be a innovative high-frequency power Tuning of the power conversion is hot topic. electronics topologies, for which no done via change of algorithms or analogue ICs are yet available. This parameters. By adjusting the software, LED professional: What are the translated in considerable the same micro controller can be advantages of these types of digital miniaturization and power conversion tailored to control a wide range of solutions in general? efficiency gain, as illustrated by the advanced power converter topologies. market leading 2x size reduction for Digital features like DALI interfacing or Peter Deixler: We believe that digital/ our 50W indoor digital driver product. advanced features are directly done by programmable solutions will create a Figure 1: the same power-conversion micro- competitive edge for lighting fixture The full-digital approach of the controller, rather than having the manufacturers. In our digital LED Philips Xitanium cost-adder of an extra microcontroller. drivers we use software for 50W DALI driver customization and diversity (foreground) yields This is quite different to the “classic management, such as flexibly setting a 2x size reduction Analogue” Driver Approach, where the the LED driver output current in factory compared to its analogue control loops of power convertor are or in field. predecessor realized either with analogue (background) electronics components or analogue In the SSL lighting, keeping the edge ASICs, which are optimized only for a against completion will mandate a fast limited number of power topologies. innovation heartbeat, which points towards frequent software updates rather than keep changing the This digital driver already has a very hardware. If we look further into the high degree of silicon integration. All future, the “Design for Recurring control of the power conversion and

DALI networking is integrated in one examples for new digital opportunities the backwards compatibility to single piece of silicon, which features include multisite tele-management conventional lamps such as halogen or both the digital logic, flash memory, solutions in shops and energy-saving GLS to the end-user. and optimized analogue “peripheral” audit and services driving accelerated functionalities controlling the power renovation of the installed base. LED professional: On a long term MOSFETs directly. run, are there perhaps better LED professional: Before we go into concepts for home applications, for When it comes to passive components more depth and discuss the example, solutions like switch- integration into silicon, we have been advantages for the commercial dimming (Consumer SSL 2.0)? following it for quite a while. While applications, let’s have a look at recent technological progress on consumer products. Today, the Peter Deixler: For applications integrated high-density capacitors is mainstream for low-cost dimmable requiring individual control of lamps impressive, as soon as you also solutions is based on phase cut or (rather than the traditional group- embed passive elements such as Triac dimming. control), digital interfaces beyond capacitors and inductors into silicon, Is this really the right solution, or phase-cut will be used. For the your integrated semiconductor module doesn’t that just make sense for long-run, we in Philips believe that for pretty quickly becomes inflexible. This replacement lamps for the time homes RF is the most promising is fine, as long as you have a very being? candidate for SSL 2.0. RF offers full mature electronics design and high flexibility for new “green-field” lighting levels of manufacturing volume to Peter Deixler: In Europe alone, more applications way beyond what can be economically justify the peak design. than 120 million wall dimmers are done with wall dimmers or wired installed in homes. The US has another connectivity such as DALI. Especially LED professional: In your 150 million phase-cut dimmers. Having for residential renovation and DIY, presentation you differentiate all these consumers call their having lighting controls requiring between light sources and consumer electricians to replace their wall “no-new-wires” is a key enabler. We luminaires used primarily for home dimmers would hinder the adoption of expect that in a few years the cost per applications, and more sophisticated energy efficient LED lighting. Hence for RF control node will be significantly solutions like the systems for us, a true “Retrofit” will require LED lower compared to schemes commercial applications. lamps, which have a performance communicating via the existing Are both applications equally well similar to incandescent dimming with electricity wiring. This is because the suitable for applying the digital the existing legacy wall dimmers. RF bill-of-material is dominated by approach? high-price-erosion digital and low- Where do you see the main Making a 6W LED lamp function voltage components shared with the IT differences? flawlessly on a dimmer requiring a and telecom industry minimum load of 60W is a technical Peter Deixler: For consumer lighting challenge. There are also several LED professional: One definite products, right now the critical different dimmer types. The good challenge for the SSL industry is the success factor is compatibility with the news is that first LED lamps are MR16 replacement, due to the existing legacy infrastructure, such as becoming available, which are compact size (thermal management) wall dimmers and low-voltage compatible with both leading-edge and the requirement to work transformers. (Triac) and trailing-edge (MOSFET) flawlessly with any Halogen 12V dimmers. For instance, in the recently transformer. Regarding future lighting control announced Philips 60W-replacement What is your opinion about that? applications for homes, they need to LED lamp, we have cracked this nut by be in line with the consumer market pulling the highly non-linear dimmer We in Philips have just introduced boundary conditions on interaction problem into the digital 50W-and 35W low-voltage halogen commissioning, security, ease of use, domain. replacement lamps. These MR16 network scale and cost. Therefore retrofit lamps, work flawlessly on any Philips is active within the Smartlight For serving simple group-dimming Halogen 12V transformer while saving consortium to create a simple and applications, we believe that a up to 80% energy. The transformer sensible industry specification for RF fine-tuned interface between phase- compatibility is enabled by a patent- control of over-the-counter lamps and cut dimmer & LED lamp will still be the pending LED lamp electronics Luminaries in the consumer market most affordable group dimming control breakthrough. space. in the future, both at a lamp and system level. We see that first dimmer We also have first dimmable MR16 For commercial building applications, manufacturers are releasing new products, which are compatible with the lighting solutions are typically larger phase-cut dimmer products, which are existing 12V transformers and some of scale and often require PC-based especially suited to SSL, but still offer the installed-base legacy phase-cut commissioning by an expert. Typical dimmers

LED professional: Regarding the LED modules, and a further step is light-source modules, rather than commercial market, up until now, a the integration of the electronics in getting their own soldering iron out system has often consisted of a the LED module. Philips supports and continuously upgrading to the control, a supply, and an LED driver. both approaches with different latest LEDs. Every single stage has its specific versions of Fortimo modules. losses. Do you see application-specific When it comes to the lamps and gear Can the digital approach join these distinctions in the degree of manufactures, I believe that vertically components without sacrificing the advantages? integrated players, such as Philips, quality and at the same time Are there additional advantages (for spanning from LED components, possibly help to save additional instance costs)? ballasts to LED lamps/modules are energy? placed well in the world of digital Peter Deixler: When compared to LED lighting; they can determine their Peter Deixler: Indeed we have systems with external driver, the overall LED system architecture solely achieved with integrated electronics integrated electronics will certainly on what integrally gives the highest very high efficiencies compared to a lower the required initial investment for value & simplicity to the customer. stand-alone driver, especially for the certain LED applications. For example, low to medium driver wattages. As the we expect that the integrated- LED professional: Finally, I’d like to driver wiring to the LEDs cannot be electronics Philips LED modules in the ask you a question apart from the touched, fully integrated solutions can 300 to 800lm range will enable faster digital approach. There are many omit the electrical safety isolation market penetration of LED systems in other trends in LED lighting. required for stand-alone drivers. This the price sensitive hospitality and Which is/are the most important opens the door to innovative consumer segments. The integrated one/s for you personally? electronics topologies with lower driver electronics is also leading to component count and reduced breakthroughs in system compactness Peter Deixler: I personally find the electronics waste, which is an and flatness. For high lumen high-speed inroad of TLED (tubular important aspect for cradle 2 cradle. applications, such as street-lighting LED) very exciting. We have just Above all, for the customers, the and offices, I still consider stand-alone globally launched a TLED lamp integrated driver electronics enables drivers as the best approach due to product, with T8 form factor. First easy-to-use modules, which can be thermal considerations. Philips TLED applications examples connected directly to mains (230V AC). include hypermarkets in Indonesia and Figure 2: However, the high-temperature Singapore (Figure 3), where The Philips Intuos LED disk replaces environment within integrated sustainability plays an important role. 60W halogen and light-sources places requires careful We also see commercial traction incandescent driver electronics design. whenever TLED successfully lamps for addresses TL limitations, such as in hospitality LED professional:The integration of vending machines, 24/7 covered car and home applications. the controls part seems to be one of parks or extremely dusty industries, The integrated the biggest advantages. where TLs often have maintenance electronics What are the advantages of adding factors of 0.5. enables a cost- intelligence to the ballast, for effective and small example, new functionality? To decide for which applications TLED module LED professional: All these aspects or conventional TL makes sense now, Peter Deixler: For example, our have a big influence on the lighting it is important to assess the lux level on outdoor digital driver is recording the industry. the task area rather than following times when the municipality is Will there be classic luminaire overly simplistic lm/W comparisons at switching the power of their streetlights manufacturers or ballast lamp level. The directional nature of the on and off. Based on the information of manufacturers in the future, or will TLED has an intrinsic advantage over the last three days, the driver SSL change the industrial TL light, which for instance encounters determines the month and then applies landscape? up to 35% optical losses in bare batten an optimized timing profile of the light fixtures. output over the night. In June in Peter Deixler: For the lighting industry, Holland, we use a light-output profile LED is a rather disruptive new Many people are concerned about with lower peak intensity than in technology. LED lamps and LED seemingly exaggerated lifetime claims January. modules for mainstream applications and the spotty appearance of tubular will be a high-volume-electronics LEDs: LED professional: The digital driver environment, where economy of scale I recognize that many TLED products concept can also enhance other and fast innovation are ruling. Hence with questionable records are entering technological trends in SSL lighting. we believe that the luminaire the market. We have just tested a One trend is the implementation of manufacturers will leverage LED product, where an installer inserting

Figure 3: this specific TLED tube without Giant supermarket, switching off the electricity, is directly Jakarta, exposed to a mains-voltage shock at Indonesia. Project the end-cap. In the Philips TLED with a total of product we have put great emphasis 4000 Philips on system safety under foreseeable MASTER LEDtube misuse, next to fulfilling the lighting regulatory requirements on glare & uniformity and meeting the user preferences regarding the tube`s uniform visual appearance. We base our 30k-hours lifetime predictions for TLED onto calibrated models based upon many years of fluorescent and LED expertise in Philips.

LED professional: Thank you for discussing the most recent SSL trends and digital drivers, with LED professional.

Peter Deixler: Peter Deixler has been working as Peter Deixler studied Technical Global Senior System Architect at Physics at the Kepler University in LED Lamps & LED Systems Philips, Linz, Austria, and Microelectronics at Eindhoven, Netherlands since 2006. the University of Manchester, Institute of Science & Technology, U.K. From 1998 to 2006 he was Lead Architect for RF Process Technology During his leisure time, he enjoys & SSL Emerging Business at Philips mountaineering and skiing, or visits Semiconductors/Research, New and listens to operas. York, Eindhoven & New Mexico.

Intelligent Lighting (Part II): From Definition to Implementation

While Osama Mannan, Technical Marketing Engineer of Future Lighting Solutions presented the different technologies used in an intelligent lighting system and the benefits that can be achieved using different approaches in Part I, in Part II he explains how the features presented previously can be implemented with different levels of complexity, depending on the location and the requirements of the application.

Figure 1: Looking closely at an intelligent ON, or vice versa. Alternatively, a a A simple intelligent lighting system, the DALI-based sensor can be used to controller and implementation of the system broadcast the signal to all the fixtures sensor system comprises of a combination of a in the room and trigger the same wide range of products action. Although communication using depending on the application and DALI can address each fixture and its requirements. This article will control them individually, a simple focus on three implementation implementation of DALI would only approaches and the products require one signal to be broadcasted that can be leveraged to develop and initiate control to all the fixtures the intelligent lighting system. collectively. The sensors can work with a controller, which can be installed Basic and Direct Control either stand-alone or integrated inside b A key feature that intelligent lighting the LED driver. An example of such a control brings to LED lighting systems system is Philips ActiLume. Combined is dimming. In indoor applications, the with a pre-programmed controller, most basic form of dimming can be these systems consist of miniature achieved by using wall dimmers at a ambient light and motion sensors that fixed location in the room. Standard can be set for different modes of wall dimmers send different types of operation giving the system more signals for controlling the brightness of versatility based on the requirements. As for a simple implementation of an the LEDs, namely TRIAC, 0-10V, and The controller also includes a power outdoor application, the use of sensors DALI, and 12V Pulse Width Modulation relay, which enables ON/OFF switching can be eliminated and a programmable (PWM). The dimmer has to be of the light fixtures. Figure 1 dimming controller can be used to interfaced with an LED driver that demonstrates the functions of such a schedule actions. For example, Philips supports any of these signals in order system when installed in the luminaire. LumiStep dimming controller, which is to ultimately control the light levels of a standalone controller, but has also LED luminaires. There are several In Figure 1.a, the motion sensor been integrated inside some LED dimmable LED drivers available on the detects the absence of movement in drivers, provides pre-set dimming market from a number of vendors, the room and sends the command to modes based on the need of the offering various output voltage ranges the controller to turn OFF the lights. application. The controller will set the and drive currents to support several Similarly, Figure 1.b shows the ambient driver to dim for a certain period of LED configurations. light sensor sending the signal to dim time depending on ON/OFF switch the LED luminaire due to the points. The dimming options include 6 Additionally, a simple sensor system appropriate level of illumination hour and 8 hour dimming periods can be added to trigger dimming or provided by the sunlight. This depending on the requirements and ON/OFF switching. For instance, a operation will ultimately lead to energy product selected. A dynamic timer motion detector can be placed in the savings by reducing the power changes the dimming mid point as room to sense presence and send a consumption of the luminaires when time passes. Figure 2 shows an outline 0-10V signal to the driver to change the not required. of the controller concept implemented state of the LED fixture from OFF to in street light poles. For instance,

Figure 2 (left): Dynamic dimming control for street lighting

Figure 3 (right): Programmable dimmer control for street lighting offer additional options

considering the 8 hour dimming Local Wireless Control of a unified protocol that can be option, the controller will dim the lights The basic intelligent lighting installed in the wireless modules is by 50% two hours before the midpoint implementation can be enhanced in a Synapse’s operating system SNAP®. and then go back to full intensity six local network that includes Since SNAP is a network operating hours after. This implementation option communication between fixtures and system, it can be installed on multiple is commonly known as “2+6”. controlling them wirelessly. microprocessor based platforms such Depending on when the lights are as communication modules from switched ON and OFF, based on For wireless communication, whether various vendors or 8 to 32-bit season for example, the dimmer will it’s an indoor office using a 2.4GHz microcontrollers and radios from adjust the midpoint and dim the lights band or an outdoor parking lot multiple IC manufacturers. It enables a accordingly. leveraging sub-2.4Ghz frequencies, RF robust mesh network that provides engines integrated into the controllers embedded intelligence and secure A more feature rich dimming control and LED drivers can enable intelligent communication for connecting devices can also be achieved, for instance by lighting features within the local with each other, requiring no setup and using Philips Dynadimmer. This boundary of the application, such as a minimal application development. It’s controller, which can also be either room, a building, or a parking lot. As a also a multi-hopping and self-healing inside or outside the driver, sends a result, there is no wide area network or system that supports software update 1-10V signal to LED drivers and a need to send data over the Internet. over-the-air. initiates dimming time and levels based For lighting manufacturers who want to on configurable schedules. The design and develop their own Although developing intelligent lighting dimming schedule in the dimmer is set controller, the RF engines or IC’s can systems that directly leverage via a programming kit or computer be incorporated to the controllers or communication modules provides a software. Figure 3 shows a dimmer drivers. Such RF modules are available high level of flexibility, many lighting schedule implemented for street lights from Synapse Wireless. By adding manufacturers may not have the to follow a specific dimming schedule some additional circuitry to the system, required competencies to design to ultimately achieve energy savings. these RF engines can be configured to custom controller solutions. As a provide a digital or analog signal and result, these lighting manufacturers In summary, the most basic form of can interface with many LED drivers to require a plug-and-play solution that control is to send the control enable wireless control. The use of would seamlessly connect to their commands directly from one such RF engines enables more existing system and achieve the same component to the other, such as sensor convenient control of light fixtures as wireless control capability. One signals to the LED drivers, without well as eliminating the need for example of a finished system feedback or monitoring capabilities. In additional cable connections between component that already integrates a Figure 4: this case, there is no need for wireless the controller and luminaires. Figure 4 communication module is the SNAP Wireless control using Synapse RF communication RF modules or illustrates how a Synapse RF engine DIM-10. Engines metering devices in the system. can replace the physical link between the dimmer and the LED driver. The As illustrated in Figure 5, the SNAP extra circuitry required to send the DIM-10 can be connected to multiple appropriate signal to the LED driver is LED drivers, which enables a simple not shown in Figure 4. approach to group and control up to 10 luminaires. Furthermore, most For a lighting system to communicate dimmable LED drivers do not dim and interoperate seamlessly, the down to 0%, which means that the communication modules must share user cannot directly “switch OFF” the the same protocol or network lights. Therefore, the module also operating system (NOS). An example includes a power relay that turns off

Figure 5: One drawback of a DMX system is that An RF controller module connected it requires a great deal of cabling to to multiple drivers control several light fixtures spread and fixtures apart at different locations. Consequently, implementing DMX control wirelessly could significantly simplify the installation of the lighting system. Wireless DMX control can, for instance, be accomplished using a SNAP DMX controller, which enables wireless communication between a standard DMX console to existing DMX 512 installations without the need to modify the original equipment.

Figure 6: This DMX controller can be leveraged DMX implementations in various ways. As shown in Figure 6, the module can provide a completely cable-free implementation by connecting a module to each fixture and communicating wirelessly, as in Figure 6a. Another method is implementing a hybrid system which connects the DMX console to one DMX controller that communicates wirelessly to another controller connected to the first DMX lighting fixture. Other DMX fixtures are then physically wired together from the first fixture as they would for a traditional DMX installation, as shown in Figure 6b. Finally, if the DMX console is replaced by a computer, the DMX controller includes a USB port with the appropriate USB-to-DMX conversion capabilities. As a result, third party PC-based DMX software in combination with the DMX controller can be leveraged to send wireless DMX signals to the other DMX controllers, as shown in Figure 6c. For control from a computer, SNAP Stick, which is a compact wireless device with a USB interface, the same size as a standard USB memory stick can be leveraged. It enables plug-and-play wireless control of the SNAP DMX controller, since both communicate using the same operating system the power to the LED driver at low motion detector would send signals to (see Figure 6d). dimming levels. There are two primary the SNAP DIM-10 to trigger actions. versions available, one that supports Additionally, an LCD remote control All the components mentioned serve a 0-10V and PWM dimming signals and can be employed to control all the local network of control that does not the other that supports digital lighting lights connected to the module within go beyond the application boundaries. protocols such as DALI. It can receive the area of coverage. That is, no wide area communication is the control commands from various established via the Internet, a cell sources. As shown in Figure 5, a Besides the standard dimming control phone network, or remotely via a wireless wall-mounted dimmer can be signals, such as 0-10V, DALI, and 12V monitoring base. used to control the lights from a fixed PWM, intelligent lighting can be location. Also, an ambient sensor and achieved via the DMX 512 protocol.

Figure 7: These, in turn, are connected to Communication using a gateway energy metering modules that measure current and voltage. This entire local network connects through the Internet to remotely monitor the system performance and send out actions accordingly.

This type of arrangement enables control and monitoring of fixtures in groups. That is, the SNAP GridSense will take measurements from all the modules connected to it as a whole, and not for individual light fixtures. Similarly, all the light fixtures connected to one DIM-10 module can be controlled collectively and not separately. This approach allows for the amortization of the cost of the Wide Area Control from the Internet to multiple wireless intelligent lighting components across Implementing intelligent lighting on a modules, to enable dimming, luminaire multiple luminaires in order to larger scale allows for full control over grouping, and scheduling for the accelerate payback. the lighting system from multiple lighting system. locations and enables comprehensive However, if there is a requirement to monitoring capabilities. These systems Furthermore, taking measurements of control and monitor each and every are designed to be scalable with the parameters such as current, voltage, luminaire, intelligent LED drivers that ability to add locations and metering and power factor adds monitoring and incorporate the energy metering and functionalities with feedback for energy metering capabilities to the control capabilities is the most cost corrective actions. system, which enhances energy effective and flexible approach. Not management options. This information only does this approach enable better Communication via the Internet makes can be relayed to the Internet and control, it also minimizes the number of it possible to control fixtures without stored to a database where reports components, which greatly improves the need to be near the physical can be generated or immediate actions the system from an efficiency and cost location of the lighting installation. This can be triggered if necessary. There perspective. gives more flexibility to the lighting are several energy metering products system and the convenience of that facilitate this task, such as SNAP Some companies are developing a controlling the lights from anywhere. GridSense that captures and sends family of intelligent LED drivers that For example the SNAP Connect E10 energy metering data to the Internet. incorporate the energy metering and interfaces with other modules that use control functionalities provided by the the SNAP network operating system A complete hardware system solution components as seen in Figure 8. connects them to the Internet. As is presented in Figure 8. The system These fully programmable LED drivers shown in Figure 7, the E10 gathers makes use of all the components support dimming control using 0-10V data from all SNAP-enabled modules, needed for a comprehensive intelligent and DALI and accept universal input where a user can monitor single or lighting system. In the figure, sensors voltages. They also have an integrated multiple lighting installations via a send signals to DIM-10 modules that control for timed dimming schedules. standard web browser. The web- trigger actions in the LED drivers to interface can also send commands initiate actions in the light fixtures.

Figure 8: Complete hardware system solution

Figure 9. Complete system solution with programmable driver

Figure 10. Complete wire-free communication and control system

Figure 11. Web- For luminaire manufacturers that want communication with sensors, based software for commissioning to provide constant light output over controllers, and switches allowing for and control via the time, these drivers also allow the complete wire-free communication and Internet luminaire manufacturer to program a control with a link that runs all the way curve that will automatically increase from the light fixture to the Internet. current over the lifetime of the luminaire to offset the LED lumen depreciation. The lighting system monitoring and The driver also collects diagnostic data control from the Internet is achieved by such as voltage, current, and using a standard web-based software temperature. that provides the user with full control over the system regardless of the Conclusion All these control and monitoring location or control device used. Figure The implementation of intelligent capabilities in the driver can be 11 shows an example of an application lighting can include different accessed via the DALI protocol. As a layout from which the user can set components with different levels of result, the DALI version of the DIM-10 different control criteria to each section complexity depending on the can set the drive current and driver and assign different actions application and required features. The dimming level as well as read all the accordingly. The lights can be solutions presented in this article are diagnostic data in the driver in order to individually controlled or as groups of either already available or will soon be send the data over the Internet via the luminaries, where sophisticated accessible in the coming months. gateway. Figure 9 shows how the schedules and scenes based on Whether the system is implemented programmable driver can connect to seasons or holidays can be with the most basic components for fixture-based DALI-compatible sensors incorporated. simple dimming and sensing, or and replace multiple components, thus incorporating more functionality such simplifying yet enhancing the system. The software can also be used for as energy metering and wireless commissioning the lighting system and sensor interaction, an intelligent control However, the ultimate goal is to have a allocate functions and rules to the light system takes lighting design a step completely wireless system that fixtures based on their role and further and allows for the development involves a minimum amount of wiring location. Alternatively, basic of lighting products that enhance the yet provides complete control over the commissioning can be achieved by energy saving and performance value system. Figure 10 shows an intelligent using the remote control at the lighting proposition of solid state lighting. LED driver that incorporates wireless installation location.

TECHNOLOGY TUNABLE WHITE LIGHT 38

Understanding the Pitfalls of Tunable White Light LED Systems

Madhan Kumar and Sachin Gupta from Cypress Semiconductors uncover the secrets of color space and offer solutions that allow fine tuning a white light LED source. This is becoming more of a requirement rather than a sophisticated value-added feature.

Figure 1: Undoubtedly, color plays a An object illuminated with significant part in our perception light sources of the world around us. We have of different CRI often experienced situations values where the same object appears differently when illuminated with different light sources, giving the impression that the color of an object is also tied to the light source used. This property of the illuminating light source can be quantized as CRI [Color Rendering Index]. The CRI defines how accurately a Before we jump into the topic of whole spectrum with its own spectral sample light source reproduces tunable white light, let’s briefly response. This means that at each an illuminated object’s color in understand the concept of color. wavelength of the incident spectrum, comparison to a reference light Interestingly, color cannot be quantized the spectrum strength at that source of comparable color as easily as other attributes like wavelength is multiplied by the spectral temperature. Figure 1 shows temperature or density. This is response of the cone at the same an example where the same because the color of an object wavelength and all the products are object appears differently when depends on the physics of the object, added to give the resultant response of illuminated with light sources of the environment, and the the cone. In the end, what the brain different CRI. characteristics of the perceiving eye, perceives is a combination of the among other factors. results of the three cone types. The White light is the most common light three cones are generally termed L, M, source used, be it in home, industrial, What humans perceive as color is and S for Large, Medium, and Small, or architectural lighting. As each object actually electromagnetic spectrum in referring to the fact that the peaks of is rendered best under a specific light the wavelength range of 390-750 nm. their spectral responses are at different source, it would be a privilege if the The human eye, in general, observes wavelengths. user had an option to finely tune the each element of the image on the white light source until the object retina with three different ‘cone’ types White light is a combination of various under observation appears at its best. which serve as photo detectors. What wavelengths. If we pass white light The tuning of the light source may be makes things interesting is that the through a prism, we can see the critical in some applications, like spectral response of each of these various component wavelengths (see medical lighting. Here, we shall analyze cones is different. This means that Figure 2). The component wavelengths the characteristics of white light and when a portion of retina is exposed to range can be given by VIBGYOR (Roy the ways and means to tune it. a visible spectrum, the response of G. Biv backwards), with V-violet having each of the cones will be different. the lowest wavelength and R-red Actually, each ‘Cone’ multiplies the having the highest.

Figure 2: ‘Y’ represents both the luminance and triangle covered by R,G and B. Once Prism splitting white light into one of the coordinates. we determine this, we need to its component calculate the mixing proportions of R, wavelengths To make things easier, these three G, and B to achieve the desired color. coordinates (X, Y, Z) were further By mixing proportion, we mean the reduced to a two-dimensional space, dimming level required for the R, G, with the definition of chromaticity and B LEDs. There are many co-ordinates (x,y) as algorithms for these calculations. One In general, white light can be produced such algorithm is the matrix approach, using the three basic colors of Red, x=X/ X+Y+Z (2) with the steps below: Green, and Blue. The question for y=Y/X+Y+Z (3) developers is how to determine the 1. Calculate matrix A as: right proportion of the basic colors to So, the complete visible spectrum was achieve white. Even if we arrive at the represented in a two-dimensional right proportion, in what units are we space, named the CIE chart. going to express it, so it is widely Figure 3: understandable and acceptable? The CIE chart CIE (International Commission on Illumination, derived from its original French name) xyY color space is the most common answer for this. The xyY 2. Make the inverse of matrix A: color space is built on the concept that any color can be represented fully by its hue, saturation and brightness/ luminance in a three-dimensional color 3. Calculate the required lumen space. Though brightness and level for each of the R,G, and B luminance are slightly different, we will LEDs as: ignore this difference for the time being. In the xyY color space, x represents hue, y represents saturation, and Y signifies brightness. ‘Y’, which is equivalent to luminance, Before we further analyze the CIE xyY can be imagined as being vertical to color space, let’s briefly look at how it the (x,y) graph. Any color can be

was arrived at. In the 1920s, extensive described by the (x,y) chromaticity Here, Yred, Ygreen, and Yblue give the experiments were done on quantifying coordinates and luminance ‘Y’ . required lumen output for each of the color. One such approach was to basic R, G, and B LEDs to achieve the quantify and express color with three One critical property of the CIE chart is desired color. This method has two

coordinates – R, G and B. Here, each that any color on a straight line joining advantages. If any of the Yred, Ygreen, or

value referred to the proportion of the two colors can be produced by Yblue is negative, then it means that the 3 primary colors [R, G, and B] required appropriately mixing the two colors at requested color is outside of the for generating the specific color ‘C’: the endpoints of the straight line. For gamut of the RGB triangle. Second, if

example, any color on line MN can be any of Yred, Ygreen, and Yblue is greater C = R.R+G.G+B.B (1) produced by mixing M and N in the than the maximum lumens of the right proportion. Extending the same respective LEDs, then the lumens of

R, G and B represent the primary logic to triangle RGB [with vertices as the final color, Ymix, is too large and colors and R, G and B signify the Red, Green and Blue color sources], needs to be scaled down. required mixing proportion of the any color within the triangle can be primary colors to get color ‘C’. produced by mixing R, G and B in the Assume that we are using a PWM of However, this format had an issue right proportions. Considering this, resolution ‘N’ for dimming, then the where the coordinate ‘R’ was negative let’s treat the R, G and B color sources signal density for the PWM driving the for a few colors. To overcome this, a as LED light sources. Let the Red LED can be expressed as below, new color space XYZ was defined, chromaticity coordinates of these where Ymax,red is the maximum

where X, Y and Z are imaginary LEDs be (xred,yred),(xgreen,ygreen) and lumens of the Red LED:

primaries such that for all the possible (xblue,yblue). N colors, none of the co-ordinates are DimValuered = (Yred/Ymax,red) * ((2 )-1) negative. In this new representation, If we wish to get color ‘C’ with

color ’C’ is X.X+Y.Y+Z.Z, where X,Y,Z co-ordinates (xmix,ymix) and with In summary, the requirement for

and X,Y,Z are similar to R,G,B and luminance ‘Ymix’, then the first task is to generating any color within the triangle

R,G,B as defined earlier. In this system, check if this (xmix, ymix) falls in the RGB is basic Red, Green, and Blue

LEDs with known (x,y) chromaticity coordinates and maximum lumens. Using suitable algorithms, we would have to calculate the dimming values for the R, G, and B LEDs to achieve the desired color. One such algorithm is the matrix approach we discussed earlier.

Logically, white light used for general illumination also falls within Figure 5 : Typical LED electrical system the triangle RGB and any shade of white light can be obtained by mixing

R, G, and B sources in the right the (xwhite, ywhite, Ywhite) coordinates or With LEDs, another design challenge is proportion. It is time to introduce the expected CCT of the output white that they come in various bins, where another important parameter which is light. Based on this, the system has to LEDs falling under one specific bin used to measure the chromaticity of calculate the required dimming levels exhibit similar spectral properties. white light, the CCT parameter. CCT for the component R, G, and B LEDs. When we procure a number of a [Correlated Color Temperature] is specific color of LEDs from a vendor, based on the concept on Color Figure 5 shows a typical electrical they may not belong to the same bin Temperature [CT]. Planck’s law gives system for driving LEDs. and therefore produce slightly different the intensity of the energy radiated by outputs. The option for designers is to a black body as a function of A rectifier is used to convert line either procure LEDs under the same wavelength and temperature. voltage (AC) into DC. In general, the bin, which can be quite expensive, or Therefore, every CT has a unique color LED fixtures in home lighting/ compensate for this difference in associated with it, defined by its architectural lighting are controlled firmware. This means the load on the chromaticity coordinates (x, y). CCT is from a common master and the LED driver in terms of firmware defined as the temperature of a black fixtures are slaves. The common includes the actual color mixing body radiator whose chromaticity is communication interfaces used in algorithm, with the additional closest to that of the light source on a lighting networks are the DMX and temperature compensation and perceptually uniform color space. DALI interfaces. In a tunable white light binning compensation techniques. In Figure 4 gives the black body locus on system, the master can communicate addition, it can be an added advantage

the CIE chart. the expected (xwhite, ywhite, Ywhite) output for many applications if the LED drivers to each of the slave fixtures through support the DMX/DALI interfaces, as FIigure 4: these communication protocols. this enables a single-chip, cost- Black Body Locus Another option for the master is to effective implementation. on CIE 1931 communicate the desired CCT of the white light. It is then the job of the LED There are many controllers well-suited

driver to calculate the Yred, Yblue, and for driving LEDs, with integrated

Ygreen values and drive the LEDs with MOSFETs, CSAs [Current Sense the calculated dimming values. Amplifiers], hysteretic controllers, and other peripherals. Mixed-signal LEDs show variation in spectral controllers also offer multiple properties with temperature. modulation blocks like PWM, SSDM, Effectively, this means that their (x,y) and PrISM for controlling the dimming coordinates change with temperature. level of LEDs. A hysteretic controller, This can be critical in tunable white for example, takes the feedback from light applications, where the user the CSA, Modulator block, and the Trip would have set the dimming level for input. The trip input can be used to the R, G, and B LEDs to get a desired shut off the LED channel in case of any Note that a particular CCT refers to a white color at a specific temperature. extreme current or voltage conditions. line of chromaticity on the color space But, with variation in temperature, as The calculated Y-red, Y-blue and instead of a single color. For example, the (x,y) coordinates of the basic LEDs Y-green dimming values can be fed as points A and B have the same CCT but changes, the output deviates from the the signal density values for the different (x,y) coordinates. White desired color. As such, temperature modulation blocks controlling the Red, lighting for general illumination usually compensation techniques have to be Green, and Blue LED channels. The falls in the range of 2,000 to 10,000K. implemented in firmware with a CSA is used to monitor the current So, the input parameters to a tunable real-time temperature feedback through the LED. The hysteretic LED white light system can be either system, along with efficient heat sinks. controller output goes to the gate of

the FET, which acts as the controlling switch in a standard Buck or Boost converter. These controllers can support multiple 4 LED channels. Figure 6 shows the top-level set up for driving a single LED channel in buck configuration

The firmware for the mixing algorithm, as well the firmware for temperature compensation and binning compensation can be run directly on the controller. Furthermore, it can support the DMX/DALI interfaces.

In conclusion, giving the user an option to finely tune the white light source is becoming more of a requirement rather than a sophisticated value-added feature. Considering that in lighting fixtures, space is a major constraint, it is imperative that designers choose an LED driver which can implement a system using a single chip solution while also having the computational capacity to support complex Figure 6: LED drive circuit using the PowerPSoC mixing algorithms and seamlessly integrate them into existing lighting networks.

Dr. Michael Weirich from the Fairchild Global Power ResourceSM Center Europe explains that in lighting applications, high overall efficiency and power factor correction (PFC) are very important features not only at higher power levels, and also why a ballast design should have good EMI behavior and low cost. Furthermore, he describes a high power factor Flyback converter for LED lighting that implements all these features and can be dimmed with a standard TRIAC based dimmer.

Today’s power LEDs are dimability of incandescent lamps, At first glance the increased input extremely efficient light sources. using the already installed wall current seems not to be too big of a Manufacturers claim to achieve dimmers, a feature that is missing with problem, especially since energy 200 lm/W and more in their labs standard CFL. meters measure the real power and and devices with about 100 not the apparent one. But closer lm/W, similar to the best linear Importance of Power analysis shows a lot of disadvantages fluorescent lamps, are available on Factor Correction (PFC) of poor PF devices. Most important are the market. In parallel, the power An incandescent lamp behaves the power losses caused by the handling capability of the LEDs electrically like a resistor: its current is additional reactive current in the has increased, and at the time of proportional and in phase with line distribution network. Since about 10% writing, multi-chip modules with voltage. to 12% of electricity is used for lighting, a power of up to 100 W can be it is obvious that increasing reactive found on the market. Switched mode power supplies on the current by a factor of 3 to 4 will other hand always have a rectifier at considerably decrease efficiency of In lighting electronics international the input, followed by a reasonable such efficient sources like CFL or LED. standards as EN 61000-3-2 make valued capacitor, that filters and power factor correction mandatory for smoothes the rectified line voltage. Besides that, harmonic analysis of the an input power above 25 W. The new Since current flow through a rectifier non-sinusoidal input current shows a Energy-Star directive for solid state diode is possible only if the input high harmonic content that worsens lighting (SSL) even asks for a power voltage is higher than the voltage EMI behavior of the application. Since factor (PF) of more than 0.9 for power across this capacitor, there is only a line harmonics cover the complete levels above 3 W. While it’s possible to short time frame where input current audible range, influence on audio achieve the latter value with passive can flow. As a result, these short peaks equipment and generation of noise in PFC, it is desirable to have a cost must have high amplitude in order to inductors is very likely. effective solution that can achieve even transfer the energy. If the RMS value of better performance with low weight this peaky input current is measured or Flyback Basics and small form factor. A Flyback calculated, it will be three to four times For isolated power supplies up to converter controlled in such a way that higher than it would be expected from about 100 W the Flyback topology is input current is almost perfectly the actual power consumption of the well accepted due to its relative simple, sinusoidal can be the most cost device. PF can now simply be defined low component count construction, effective solution, if isolation between as the quotient of real power to cost effectiveness and at the same input and output is mandatory. apparent power: time reasonable performance. The basic operation is simple and easy to Real Input Power Besides high power factor there are PF = explain with the help of Fairchild Apparent Input Power more indispensable features of an LED Semiconductor application note ballast: high efficiency in order to get Hence, the PF of the incandescent AN-4137 (http://www.fairchildsemi. an overall efficiency comparable to lamp is one while that of the example com/an/AN/AN-4137.pdf). While the CFL and long lifetime, that has to be as above can now be determined to be in MOSFET Q1 is conducting, the current long as that of the LED itself. Finally, the range of 0.25 to 0.33, far below in the primary side of transformer T1 users would like to have the easy that of the classic bulb. ramps up linearly and builds up a

magnetic field that stores energy. The polarity dots of the transformer indicate that polarity is such that the

secondary side rectifier DRect is off during this time. As soon as the MOSFET is turned off, the polarities of all voltages across the transformer

reverse, due to Lenz’s law. DRect now starts to conduct and the energy stored in T1 is transferred into the

capacitor CFilt. Duty cycle of the PWM controller together with the winding ratio of the transformer determine the output voltage that is stabilized with the help of an isolated feedback

network. The network DCL, CCL and RCL clamp voltage spikes due to the imperfect coupling between primary and secondary, the leakage inductance. This is important to reduce the voltage stress of Q1 but at the Figure 2: Timing and currents in DCM Flyback PFC same time a source of power loss since the energy is dissipated in RCL. controller like the FAN7527. This mode controller is used, input voltage Figure 1: approach needs a high VDS in order to as a reference for the MOSFET peak Simplified schematic of a achieve a PF close to 1 and suffers drain current is not needed. Since, on Flyback based from the poor low load behavior of the other hand, current mode (CM) SMPS these controllers since they are not controller have so many advantages designed for this purpose. for standard off-line applications, it is difficult to find a state of the art VM The second, less well known approach controller for off-line applications on is to operate the PSU in DCM with the market. In general, switched mode power constant switching frequency fS and a Figure 3: supplies can work in two different duty-cycle that is constant (at least) Converting a current mode modes: discontinuous conduction over one line half-cycle. With this PWM controller mode (DCM) where the MOSFET is approach, the power factor can, at into a voltage turned on only after the current in the least in theory, achieve unity without mode one diode DRect has dropped to zero and increasing VDS. continuous conduction mode (CCM) where it is turned on while there is still Figure 2 shows the timing relationship

current flow in DRect. A third mode is during one line voltage half-cycle. sometimes mentioned: transition or Since the on-time of the MOSFET is boundary conduction mode (BCM) kept constant, the peak value of the A solution could be to use one of the where the MOSFET is always switched drain current perfectly follows the readily available CM controllers with on instantly after diode current shape of the input voltage. Due to the constant switching frequency (e.g. the becomes zero. As the name implies constant fS averaging of the pulsed FAN6862) and use the input voltage as this mode is on the boundary between input current (this is done by the EMI a reference for the peak current of the DCM and CCM. filter of the PSU) yields a shape that is switch, exactly as is done in the PFC proportional to the input voltage. controller FAN7527. Like in the High Power Factor Flyback Figure 2 also shows that the PSU FAN7527, a multiplier would then be With the right control method and almost works in boundary mode at the needed, since the sinusoidal reference some changes in the input circuitry, maximum of the line voltage while it has to be modulated with the feedback the input current of a Flyback can goes deeper and deeper into DCM as signal in order to regulate output follow the input voltage almost the line voltage drops to zero. This voltage or current. perfectly. Two different control method to achieve high PF can be methods are mainly used to implement implemented ideally with a voltage Fortunately there is a simple and easy such a high power factor (PF) Flyback. mode (VM) PWM controller and implementation trick to make a VM The first one is well known from assuring DCM operation by choice of controller from a CM controller. In both literature and uses a BCM PFC the transformer inductance. If a voltage types of control the output of the error

amplifier is compared to a ramp signal Quasi-Resonant Operation Without going into much detail it can in order to generate the PWM signal of The Flyback converter mentioned so be said that traditional QR switching the switch. In CM mode this ramp is far is a so-called “hard switching” one. has the disadvantage of increasing generated directly from the switch That means that the MOSFET is turned switching frequency with decreasing current itself, while in voltage mode the off while the drain current is high and load since the switching is ramp is generated by a built-in turned on while drain voltage is high. synchronized too, with the de- oscillator with a saw-tooth output. If Since the falling / rising current and the magnetization of the transformer. The the ramp signal applied to the current rising / falling voltage overlap in each latter occurs the faster the lower the sense input of a CM controller now switching cycle their product is not (load) current level is. Even if switching comes from a ramp generator instead negligible and there is considerable loss itself is reduced by QR switching, of a shunt, the controller works exactly power dissipation called switching loss the high frequency operation at low like a VM. Of course the ramp signal at each transition. In a DCM Flyback load spoils loss balance under these needs to be synchronized with the there is no current flow when the conditions. internal oscillator of the chip. MOSFET is turned on, but the inherent

capacitance CDS of the MOSFET has to Consequently, state of the art QR This can be achieved as shown in be discharged and the energy stored controllers use an improved Figure 3 by removing the connection in this cap has to be dissipated. If one mechanism for the detection of from R2, the current sense shunt, to keeps in mind that the stored energy is minimum drain voltage. The

x 2 the current sense input and adding R1, 0.5xCDS VDS it becomes clear that it is FAN6300A, for example, has a certain C1 and Q2. The latter is a self advantageous to turn on the MOSFET minimum time of 8 µs while the conducting p-channel JFET that ties with as low VDS as possible. synchronization circuitry is disabled. current sense to ground as long as its Only after this time has elapsed, can gate and that of Q1 are drawn low. In a hard switching Flyback operating the next drain voltage minimum be When the internal oscillator initiates a in DCM it can be noticed that the drain detected. The result is the detection of switching cycle the output of the voltage shows oscillations right after the umpteenth minimum drain voltage controller rises to about 15 V, turning the energy has been transferred oscillation instead of the first one. If this on Q1 and turning off Q2. Now C1 is completely to the secondary and the minimum off-time is increased with charged via R1 from the supply voltage transformer is de-magnetized. This decreasing the feedback level, i.e. of the chip, applying an almost linear oscillation is caused by the primary decreasing load, it is even possible to ramp to the current sense input. As side inductance of the transformer Lp decrease switching frequency with soon as the ramp voltage hits the level and the drain to source capacitance of decreasing load current, resulting in

set by the feedback loop, the PWM the MOSFET CDS. The Quasi-Resonant excellent low load current efficiency. comparator switches and turns of the topology monitors the drain waveform gate driver. Now Q1 is off and Q2 on and detects the minimum of this Primary Side Regulation again, discharging C1. Obviously, the oscillation to switch the MOSFET on. Due to their relatively constant duty-cycle of each switching cycle With this method switching less is temperature parameter and production depends only on the feedback voltage reduced and can be reduced further at parameter, dependant forward voltage and not on the current through Q1: the the cost of increased VDS when LEDs should be driven with a constant controller works as voltage mode turned off. current. This is usually achieved by PWM. some circuitry that senses and amplifies the output current driving an Figure 4: optically isolated feedback network as Quasi Resonant Switching indicated in the simplified schematic of Figure 1. A standard way to implement this circuit is with operational amplifiers that need an additional stabilized supply voltage complicating the secondary side significantly. Irrespective of that, the opto-coupler is a component with reduced lifetime at elevated temperatures as they are observed in typical ballast applications.

This is a mechanism that omits the complex secondary side circuit and improves lifetime since an opto- coupler is not needed in the so-called primary side regulation. The latter uses

the fact that the ratio of two different Hence, the input of the actual Flyback When the ballast operates in constant output voltages of a Flyback is is no DC voltage, but consists of current mode the voltage at the dominantly determined by the winding positive half-waves with the shape of feedback pin is limited by R109. ratio of their respective transformer the line voltage. windings. If one of outputs, say the The circuitry that puts the controller

one that generates the VCC for the The controller FAN6300A has an into voltage mode is visible on the PWM controller, is stabilized, the internal start-up circuit that can be lower right. Other than shown in Figure others will be relatively stable, as well. directly connected to the rectified 3, the capacitor is charged by a mains voltage. At startup C105 is current source that increases charge If it comes to regulation of the output charged to about 15 V and the current when the output voltage, and

current, the situation becomes a bit controller starts to operate, while at the in turn, VCC drops. That gives the linear more complex. Basic calculations same time, the internal start circuit is drop of on-time with output voltage, show that the on-time of the MOSFET disabled in order to limit power approximating a constant current should vary with the square root of the dissipation. When the controller is output very well. The switching load voltage, which is not easy to active and drives the MOSFET Q101, frequency is 100 KHz, allowing the achieve. If the variation of the load supply voltage is generated from the power to be transferred with an EF20 voltage is limited to a smaller range, as corresponding winding of the type transformer. it is in the case of an LED, a linear transformer via D103 and filtered by approximation to the square root is C111. Since the voltage across the Network R111A, R110, C108 and D106 acceptable. How this is implemented latter winding is proportional to the implements an over-current limit for becomes clear from the complete drain voltage, the synchronization Q101 and is inactive during normal schematic. signal for QR switching can be operation. generated from this voltage. As Putting Bits Together mentioned before, the input voltage There are two outputs on the The operation of the actual circuit can varies from zero to the maximum line secondary side: one for driving the now be explained with the help of the voltage, and the sync signal does, as LED module having 14 V / 1.4 A and complete schematic of Figure 5. On well. The network R105 & D107 the second with 5 V / 0.2 A for a fan the left hand side the EMI filter and generates a stable signal over the integrated to the LED’s heatsink, giving rectification are visible. The MOV at the complete half-wave. a total output power of 21 W. input limits line surge voltage. The output voltage is stabilized with It has already been mentioned that The capacitor after the rectifier (C102) the network D104, R101 and Q103, duty-cycle has to be virtually constant has a relatively small value in order to while C107 is for frequency over the line half-cycle, i.e. the guarantee the intended high PF. compensation of the feedback loop. feedback loop must have a slow

Figure 5: Complete schematic of high power factor dimmable LED ballast

Figure 6: Input voltage (CH1) and current (CH3) of the ballast Figure 7: Input current and voltage with TRIAC based dimmer

response with a corner frequency Dimming of incandescent lamps with TRIAC below about 25 Hz. This is achieved by Since the ballast is running in voltage based dimmers. But since a 20 W LED relatively high values of C105 and and having a specific feedback loop, may replace a 75 W incandescent, C111. The slow loop response is not an output power is proportional to the trouble with the built in dimmer that is issue at all since the LED is not a very RMS input voltage. If the latter is rated at a 50 W minimum load may dynamic load. reduced then output power, or rather, arise. the brightness of the LED, is reduced The ballast has been assembled on as well. A second problem that may arise with two PCBs that fit into a cylinder some dimmers is due to the ringing of measuring 48 mm in diameter and The ballast has been tested with many the input filter together with C102 that 42 mm in height. This PCB was different electronic dimmers so far. So may cause faulty turn-off and re- designed to be fitted directly to a called ‘Tronic’ or ‘Phase-Cut-Off’ triggering of the TRIAC. In this case a Nuventix MR16 heatsink. dimmers that are intended for use with damping network consisting of a electronic transformers for halogen resistor of about 470 Ω / 2 W in series

With 230 VRMS input and 21 W output lamps work excellently, since the with a 100 nF / 400 V film capacitor will power an efficiency of 85% has been switching element in these dimmers is help. This network should only be measured. Due to the relatively high not a TRIAC and doesn’t rely on a added if necessary since it dissipates output current the secondary side certain hold current. some power and worsens efficiency. rectification is one of biggest sources of power loss. If the ballast is Many of the standard TRIAC based re-designed to work with higher output phase cut dimmers also work well voltage and lower current, efficiency although the situation is more will increase somewhat. complex. Since TRIACs need a certain hold current that is related to the The power factor was measured to be minimum controllable power, those 0.98 and a THD of the input current of dimmers that have a low minimum 7% was measured. A scope shot of power of, for example, 20 W are better input voltage and current is shown in suited than ones with a high value. Figure 6. This is not really different from the use

LED Waterproof Wall Light WL-030-AW-01 As the global leading manufacturer of flexible LED strips, Signcomplex has developed a new Waterproof Wall Light for solid state LED lighting. WL-030-AW-01 features IP66 waterproof, lighting both two sides. Its power consumption is 30W, input voltage is 100-240V, lumen output is 1108lm for warm white and 1342 for cool white. Both sides have 6 LED and its lens is 45 degrees. It has a bracket to be mounted onto walls, and can be widely used in hotels, homes, landscapes, parks, to highlight the architecture outline and texture, and render a magnificent appearance. www.signcomplex.com For more detailed technical and sales information, please contact SignComplex sales team.

ELECTRONICS LINEAR & PHASE CUT DIMMING 48

Facts about Dimming

Over 95% of the existing residential and commercial electrical dimming infrastructure are single channel wall dimmers. Gregg Sheehan, IP / R&D Engineer at Light-Based Technologies explains why it is crucial to serve the market with high quality solutions and how to solve the upcoming challenges.

This article is intended to address various “green-mandated” world transformers. LEDIM usually employs a “direct” phase-cut dimming of governments move towards legislating simple Triac or Triac/DIAC as the active LED fixtures and does not include traditional incandescent/ fluorescent element, while TEDIM has generally the wide range of network type fixtures out of existence, these same more complex circuitry and utilizes dimming systems such as DMX, sockets will ultimately be populated MOSFETS or IGBTs as the active DALI, 0-10 or 1-10VDC style with LED lamps as replacements. This device(s). LEDIM could be said to be control networks or theatrical latter point needs to be underscored Active State ON and TEDIM to be methods. This is primarily as the lamp fixture most likely replaced Active State OFF, relative to a zero because there has, to date, first in a given installation is the one degree starting point, per 180 Deg or been much written discussion that creates the most value, and of half-wave. It is fair to say that there is on the use of LED fixtures in these, many will likely also be slightly less inherent noise produced network control, yet less that connected to some form of single by TEDIM, as RF and EMI from addresses the larger part of the channel dimming solution or controller. TEDIM’s active state, as it is switching dimmed lighting environment – The existing wall dimmer with an off, rather than on, with less overshoot namely the use of the ubiquitous incandescent lamp works quite and resultant high frequency noise. single channel wall dimmer that smoothly and looks very appealing. It Figure 1: makes over 95% of the existing is aesthetically pleasing and Phase cut dimming types residential and commercial economical in its implementation. This Achieving “Good electrical dimming infrastructure. is the benchmark LED dimming needs Dimming” with Those acquainted with the to hit and then surpass, to be fully LEDs subject matter are familiar with embraced by the end user. the need to maintain power Unfortunately, dimmed LEDs often do factor, efficiency and stable not fare so well. Substantial power operation but the challenges to savings alone can’t make these facts achieve these goals are less well invisible to the end user who is looking understood. to re-create the effect and response of their existing lighting infrastructure. The In short, single channel phase-cut fact that the US Energy Star criteria dimmers are a significant part of the offer as a solution a request that LED existing lighting landscape and show lamp suppliers provide a list of suitable no signs of going away. In fact, sales of dimmers for their lamps is sufficient these dimmers continue to increase. evidence that the compatibility of LED According to studies done almost 9 with existing dimming technology is far years ago there were 4-billion from perfect. incandescent lamps in the US alone with estimates of over 150 million The two major types of phase-cut traditional dimmers installed. The dimmers used today (so-called forecast is for these to continue to because they remove or cut, selected increase in numbers well into the future portions from each AC half-cycle wave) and be installed into buildings and are leading-edge dimmers (LEDIM) and homes world-wide. The impetus trailing-edge dimmers (TEDIM). See behind this continued adoption is Figure 1a, b and c. LEDIM seems to be two-fold – a desire for increased prevalent mostly in North America. illumination aesthetics in increasingly TEDIM is very popular in the EU/ and upscale residential/commercial the rest of the world, supposedly environments and the possibility for working better with low- voltage “energy savings” via dimming. As the halogen lamps using electronic

Figure 2: A further refinement and advantage of PWM resolution at low dimmer one such proprietary approach offered settings by Light Based Technologies is the ability to scale a lamp’s response in a programmable way that enables finer, repeatable control over a specific area of the entire dimming range. This ability to change modes, while using a standard third-party dimmer is made possible by detecting changes in the dimmer control when doing short, repeated or specific motions. For example, a quick up/down, done in under a second, flips the mode to a The lighting industry, inclusive of LED larger (shown in Figure 12) as a different preset mode, such as Mode fixtures and lamps, generally has comparison between perceived light “B” or 40% maximum light level at full clearly defined electrical standards, levels vs. absolute power/light levels. fader or full clockwise and counter- properties, life expectancy, Compared with the ideal, this is visually clockwise rotation of a control. Figure temperature and light distribution distracting and unacceptable. 3 shows how the actuation of this standards, which are defined and proprietary “Deep Dimming” feature endorsed by the third-party Consider restaurants: They are the creates a magnified dimming certification industry, (including the IES quintessential dimmer users, with the resolution at the bottom of the LM-79 and LM-80 (now referenced by business norm being that lighting is in dimming range such that the bottom DOE as Energy Star™)). It does not, some dimmed mode, usually within the 20-50% of full range is spread out over however, have the same definitions bottom 20% of the full-light level, to the entire electro-mechanical and standards for actual dimming create the traditional intimate dining adjustment range. This is irrespective performance over the dimming range. experience. They use a nearly of the user input device or dimmer and theatrical approach, to create areas of allows for much finer control of settings The practical benchmark in the high luminance contrast ratios by that operate normally in a low dimmed industry is still the behavior of a typical having a low level background setting. The control interface may be a dimmer with an incandescent load. between tables with often a highlight rotary potentiometer, linear fader, This response just appears to be lamp or central candle placed on the capacitive sensor or “touch” type “right” to the average user’s eye/ table to create pools of lighting. After user- interface. brain-response (psycho-visual closing and during the day they may perception) to be fairly linear and also require 100% lighting levels for Another set of solutions in this smooth in performance. This smooth cleaning, and next day preparations. application of intelligent linear control, flicker-free dimming response is Also consider movie theatres. They is the ability to have multiple actual- beneficially assisted by thermal inertia have a clearly defined need for performance curves available, of the filament in the lamp and visual safety- mandated, minimums and including logarithmic, linear and persistence in our vision system. The maximums, as well as building code custom variants. They are selectable relationship between lamp output requirements. This low level “norm” by a similar method, shown above. optical power and our visual response area, is where PWM-style dimming Figure 3 shows three sets of “S”-type is in fact a log curve for an starts to show it’s warts, as it starts or incandescent-style performance incandescent lamp running from a running out of bits and acts in a large curves for example, with a different 100% light level down to a 0% light “step” transition mode, resulting in maximum level on each. Mode “C” for level. However, when many LED flicker and unsmooth light changes example would be ideal for restaurant fixtures are dimmed they can shut off (see Figure 2). use during business hours and Mode completely at around 10% to 20% light “A” would then be enabled for both level on the dimming scale due to The most elegant solution for dimming after-hours cleanup and the morning practical limits imposed by their power is the use of intelligent linear control. prep. Mode “C” would allow the supply minimum-voltage requirements. This method offers compatibility with management to really fine-tune the Furthermore, at low power levels there virtually all dimmer types and exact atmosphere they desire for their can be a transition region in the manufacturers, and greatly simplifies business, by manipulating the light dimming process/range which causes the compliance under Energy Star™ levels throughout a room. flickering or visible transitions, as the with the ability to dim smoothly LED goes through increasingly larger throughout the full range. Energy Another aspect of linear control is that steps such as in a standard Pulse Star™ currently has no specific the current is generally fixed at a lower Width Modulation (PWM)-type system. requirements other than listing which level than with PWM, which operates The PWM steps are the same size but specific equipment makes and models by varying duty cycle and thus average our visual perception makes them that will work together successfully. current, over the same ∆V as linear

Figure 3: operates. The net result is less power consumed and Magnified dimming range greater efficiency with linear controls characteristic reduced forward voltage (see Figure 4).

The use of intelligent linear control as an overall control technique shows further advantages, particularly when applied to low level light-dimming applications. The well-known LED output “droop”, inherent at higher currents is not present by virtue of the true reduction of instantaneous junction current. This effect is significant in that it represents up to a 30 to 40% improvement in overall Figure 4: efficacy as the lamp is dimmed (see Figure 6). This mode of Current versus voltage operation also delivers optimized energy efficiency through most dimmed light levels when compared to traditional PWM approaches. Figure 5 shows the “droop” (departure from linearity) for a wide variety of popular LED manufacturers for luminous flux versus forward current, at constant junction temperature.

Figure 6 offers a more focused analysis on efficiency. It clearly illustrates the change in overall efficacy of a typical Luxeon™ Rebel LED operated between PWM and linear operation at a typical 20% electrical power dimmed level. Here the effect of current droop is significantly more Figure 5: apparent in the overall LED efficacy (assuming constant Typical “Droop” in output for LEDs junction temperature). Both systems are dimmed to an as a function effective 20% electrical power level while the efficacy of the of forward linear dimmed system (100% duty cycle, 150mA) is 30% current. (Source: higher than that of the PWM dimmed system (20% duty Candlepower cycle, 750mA). forums) Linear Control Most switching-type power supply (SMPS) or LED driver topologies involve designs with separate primary and secondary “side”, or sides as in the case of multiple output supplies, and these are usually electrically/ physically Figure 6: separated by a transformer or fly-back inductor. Comparison in output efficacy at low dimmed Nearly all major semiconductor companies making power levels for dimmed supply or LED driver control IC’s, espouse the very same PWM versus linear technique of primary-side control. However, the direct (Luxeon Rebel secondary-side control of power supply or LED drivers has Data) many practical advantages, as shown with the LB4 technology from LBT.

As visible in Figure 7, it can be seen that with PWM control topology, the perceived light output is still at 20% when the actual power is dimmed to 5%. The linear approach goes very near to zero perceived light output, when the actual Figure 7: power is reduced to zero. This would substantiate the Advantage of linear secondary common PWM product specifications claims of dimming side control from 100 to only 10%.

As can be seen, the relationship between measured light output power and the perceived amount of light is quite linear, with an exponent of 0.5, from Stevens’ Power law.

LBT also uses a patent pending method to send time- relevant control info from the primary to secondary sides, which enables low delay or real-time control. Having the

ELECTRONICS LINEAR & PHASE CUT DIMMING 52

Figure 8: direct load controller on the secondary Linear dimming comparison chart side, also allows accurate delivery of load current and minimum voltage, and only when required. The differences, shown in Figure 7, include low-end resolution, less capacitance required from improved regulation, etc. Two well-known controller IC manufacturers have successfully reached 0.1%, as in one case, with the inclusion of large value capacitors, with their low MTBF, higher cost and size issues. Another manufacturer achieves this by ignoring electrical isolation requirements. Dimmer Holding Current Another factor to consider for proper Figure 9: dimmer interoperability is that all Illustration of dynamic holding leading edge-type Triac-based current dimmers (LEDIM) require a holding current due to their internal electronic component’s internal architecture and behavior. In short, they will shut off completely when current stops going through them, causing the light to flicker or even turn off during this time, depending on the driver’s ability to restart. This of course, occurs periodically, every time the AC waveform approaches or leaves the zero-voltage region.

In many designs, a holding current can be simply created by a small, simple resistor load, but this is a fixed value active throughout the entire waveform Technology’s approach. The actual during the waveform. The off-transition duty cycle, which unnecessarily amount of dynamic holding current will have a slightly gradual slope rather wastes energy. A truly efficient holding (Current R42) is actively determined by than a near instantaneous slope. The current circuit is a solution, which is both the load requirements and the result is that all dimming behaves only turned on when there is requirement of the individual Triac or poorly without a suitable holding insufficient load current and in an semiconductor dimming device. The current, leading again to the need for a appropriate minimum amount and at portion of duty cycle from dynamic holding current to deliver the particular time for the load and approximately 8 to 11 ms has a smooth operation and maximum dimmer current requirements. This suitably low impedance and very small power efficiency. requires a design which is both current, in order to suit the Triac dynamic and periodic, to perform the minimum requirement. A LEDIM-type Power Efficiency function efficiently, such as the dimmer AC half-wave waveform is Every element of an LED lighting proprietary LBT Holding Current shown at top for reference at system has its own efficiency figure design. This is a practical solution as approximately 25% dimming from full, and to date there is no such thing as Triac holding current requirements do measured post bridge-rectification, but 100% efficiency. Every component in vary substantially, according to the pre-filtering. the system has an energy loss Triac component wattage, including the driver/ power supply, the semiconductor materials variations Trailing edge dimmers or TEDIM also LED itself, the optics (lenses or and the OEM manufacturers’ internal require holding currents but for diffusers), and reflectors (where used) component construction. different reasons. The active devices and of course, poor thermal are usually MOSFETS or IGBTs. The management, which can cause a Figure 9 shows a Spice simulation devices will also stop working properly gradual change, usually downward, in illustrating both the dynamic and when there is no voltage drop across luminous output produced at the LED periodic response of Light Based them, which also happens periodically gap itself, over time.

would produce around 6 watts of heat, As a consequence, when any of these Distortion power factor (DPF): and a 1kW load producing 10 watts. specific components enjoys an 1 I1rms UL/CSA -specified temperature limits DPF = = 2 increase in efficiency, even in the range √(1+THD ) Irms on surfaces dissipating this waste heat i of single-digit percentages, the is typically 140F (60C) degrees. contribution to overall efficiency is THDi is the total harmonic distortion of significant. Due to the relative cost the load current. This definition differences in technology and the The Importance of Power assumes that the voltage stays relative immaturity of LED fixture Factor undistorted (sinusoidal, no harmonics). development and productization, Power Factor refers simply and in a This simplification is often a good

engineers are more motivated than perfect world, to the degree to which approximation in practice. I1rms is the ever, to make as many improvements the voltage potential and current draw fundamental component of the current as possible; more so than the humble, required by the load, are in-phase or and Irms is the total current; where and soon-to-be- obsolete, co-incident, for each half-cycle of the both are root mean-square values. incandescent/ CFL fixtures enjoyed sinusoidal AC waveform. Both should I1rms during their own development cycle. happen at the same time, much like in PF = DPF x I a purely-resistive load does. It is rms In general terms, power supply/driver defined as real power over apparent The result when multiplied with the units may be characterized for power. The “type” of load can cause distortion power factor (DPF) is the efficiency, by: the current to lead or lag in time, overall, true power factor or just power relative to the voltage waveform factor (PF). W = P / P or W = V * I / V * I out in out in time-base (see Figure 10). In simple terms, the driver efficiency is: Poor power factor is rarely evident to Figure 10: the residential end-user however the Example of Efficiency [%]= Pout * 100 / Pin. current waveform commercial/ industrial-level user may leading the The LED efficacy: lumen/W pay additional surcharges. If their load voltage waveform is highly inductive, for example, they The lens refractive index or general may have to install capacitor switch transparency percentage (t[%]): banks to compensate for this power loss. At the residential level, the utility velocity of light in vacuum n = company must spend money on velocity of light in medium hardware and additional power to or correct for this imbalance throughout their distribution system. t[%] = lm out x 100 / lm in, Dimmers of both styles have a major respectively, and the reflector effect on Power Factor, for all types of LED drivers and switch-mode power efficiency from loads (capacitive, inductive, resistive, supplies (SMPS) are considered to be Linear, non-linear and combinational/or non-linear or complex loads and lm out (incidental) x 100 complex). This is because it is typical require power factor correction (PFC) lm in (incidental) to cut voltage phase over the current to reduce the non-sinusoidal current peak in the same area as required by distortion they create, from having Considering system efficiency the load causing imbalance and excess energy at harmonics of the line throughout the dimming range is a harmonic distortion on the AC line frequency of the voltage (see Figure 11). necessary consideration. Does a (see Figure 11). modern Triac-type dimmer, used for The EU standard EN61000-3-2 LED and drivers, have an efficiency regulates harmonic content and basic Figure 11: PFC criteria for all SMPS. Passive PFC Distortion Power specification? Good question! Factor waveforms Old- fashioned dimmers used loss in LED drivers/power supplies usually caused by non- resistive elements while modern involves adding capacitors, resistors linear/complex dimmers are more like triggered and steering diodes, such as “valley- loads switches, particularly the MOSFET- fill” circuits. Active PFC also involves type. Still, nothing is perfect and redistributing the current over the everything has some ESR (electrical voltage half-cycle waveform. The series resistance) which wastes power problem to solve is how to improve by producing heat. During normal load regulation without adversely operation, dimmers do get warm to the “Distortion power factor” describes affecting PFC or make the load look touch. Phase-cut dimmer electrical how the harmonic distortion of a load like a linear resistor. The typical efficiency is typically around 99%. The current decreases the average power technique is to utilize a 2-stage supply/ other 1% is dissipated in the dimmer transferred to the load. driver topology such as boost, buck or as heat. So a dimmer on a 600W load buck-boost.

LBT’s new proprietary power-supply/ that power are required, in order to be users choose to dim their lights, even LED driver currently under perceived. Modern LED technology in more electricity is saved. Due to Triac development utilizes a radical new retrofit lamps can just barely achieve triggering characteristics, they do not topology to improve Power Factor the high level of brightness and quality turn on exactly at the zero crossing of performance and efficiency. that is acceptable for the mainstream the AC waveform and there is a small market. Much work remains to push amount of phase cut occurring, until Power versus Perceived the envelope of brightness, power, that voltage threshold is reached, even Light efficiency and thermal management for at the fully-on setting. The relationship between actual commercially acceptable products. dimming (light reduction) and The good news is that strides continue A summary of aesthetic performance perceived dimming (human perception to be made in this direction and LBT is attributes for high performance LED of light reduction) is logarithmic by happy to be on the cutting edge of dimming would be: Controllable nature (see Figure 12). Dimming to say, innovation, in this truly exciting field. dimming range, programmable 25% of the original full light output is dimming curve, smooth transitions, perceived as approximately 50% On the most pragmatic level, dimming good starting and warm-up, stable dimming and so forth. That being said, LED lighting saves money, in several light level throughout the adjustment a typical dimming amount of 3 to 5 % ways. This happens from reduced range, stable color or programmable dimming shows up on the last little bit direct electrical consumption and color shift during dimming, low of fader or rotary control adjustment is reduced maintenance or replacement acoustic and EMI noise, control/ user hardly ideal. A narrow dimming range costs, through to increased lifespan of input flexibility, good Power Factor and is barely perceived. Human perception the light fixture, itself. Every dimmer pleasing, comprehensive color control. of audio behaves in a similarly automatically saves 4-9% in electricity- logarithmic way, where larger amounts even at the highest lighting levels-over Good technical performance attributes of power and change proportional to a standard on-off switch. And when for high performance LED dimming are: wide-range AC input operating Figure 12: voltage, wide input waveform Perceived light level versus acceptability, highest efficiency absolute power/ possible, flicker-free and step free low light levels range performance, no cut-out, smooth full-range operation from 0 to 100%, low harmonic distortion (THD), good Power Factor , low-EMI and RF generation, minimum voltage operation, current regulation and low inrush current.

Dimming LEDS, like the less-efficient CFL, is difficult. Through careful explicit design, they can be made to perform identically, to what the end-user is familiar with, using traditional incandescent phase-cut dimmer controls.

ELECTRONICS CHARGE CONTROL 56

Charge Controled LED Drivers

Jens Göhring, Head of Technical Development at dilitronics explains why it is necessary to improve LED driver efficiency, precision and intelligence to keep pace with the progress of LEDs, and introduces a new driver technology to acheive these goals.

The starting point for the Basically the available drivers, no The Key is Charge-Control development of a new technology matter whether discrete or integrated, Imagine a parallel arrangement of is frequently a bewilderingly can be categorized in three groups: LEDs, where each connection is easy question. In the case of the constant current, constant voltage and comprised of the same number of dilitronics, this reads as: Why is pulse width modulation (PWM). Each LEDs (one or more). Applying a the development of efficient LEDs of these basic principles offers unique constant voltage to this circuit would progressing constantly while advantages and are - to some extent make currents flow with different driver technology stagnates? - easy to use in their application. With power through each channel, caused a constant current driver one might by the differences in forward voltage of In the last 20 years, LED technology have the best control over a LED the LED. The controller now compares has taken a massive jump in its system, but it will lead to complex these different currents to each other, development. Meanwhile, in the areas designs when many LED channels and then calculates and dedicates a of visualisation and illumination, the need to be driven individually. specific pulse time to every single light emitting diode has made its way Constant voltage is an easy way of channel. A channel with LEDs with a to replace the common light bulb or driving when there is only one higher forward voltage would take a halogen lamp. In order to fully exploit LED-string to be lit, but less lower current; the driver will apply a the potential of LED technology, it is predictable when uniformity of multiple relatively long pulse time. Another not sufficient to simply increase the strings is demanded. Pulse width channel, the LEDs have a lower performance of LEDs and to produce modulation became a standard in forward voltage here, would take a them more economically. To open up dimming LED and colour mixing, but higher current, so the applied pulse other applicative fields, it is also still needs compensation for the time will be short. In the end, each

important to enhance the precision Vf-spread of the LED which finally channel will most probably draw a and intelligence of the drivers. A newly means a waste of energy. Considering different current compared to the developed technology keeps up with a dynamic mode, such as change in others and each channel will be given the rapid evolution of the LED. temperature or active dimming of the a specific pulse time which equalizes LED and a multi-channel application, the charge in all channels. But, and this has become a the control of a LED-system becomes recognition beyond LED-insiders, the more complex and will sooner or later Mathematically this principle is very obstacles for applying LEDs are as hit economical boundaries. The simple. The charge is defined as numerous as the advantages. The question of electronic and optical current by time (1). And we know that production distribution in colour, designers will always go back to the the electrical charge is in proportion to luminous flux and forward voltage, the question: How much current at what the luminous flux of the LED. (2) shift of these parameters over current temperature does the single LED Q = I * t (1) and temperature, and of course the require to light up sufficiently and is it interaction of current and temperature homogeneous with others? The new Qe ~ πv (2) seem to make using LEDs a game of approach, controLED, answers this chance regarding their system question in an astonishingly simple For a multiple number of LED-channels performance (not even speaking about way: No matter at what temperature, this control results in identical charges commercial constraints). Assistance is let the LED take as much current as it per each channel and by this in a required to overcome, or at least wants, but take control of the time the uniform appearance of all channels. minimize these complications, and LED has to light up. Q1 = Q2 = …= Qn [A * s] (3) LED-drivers provide this assistance with a huge variety of specific π1 = π2 = …= πn [lm] (4) functions and features.

Figure 1: This might be a circuit with three high with external electronic devices, for Working principle of controlled power LEDs, with a Vf of LED1: 3.45 V, example cameras or sensors, depends technology LED2: 3.20 V and LED3: 3.05V at 350 on the software implementation. mA, which are operated in a parallel Through an active feedback and circuit with a constant voltage of 3.2 V. communication interface (SPI), the Each LED would consume a different application provides information as to current, shining in different intensities, which LED is active or defective The process of this equalization is part and discoloured. The controller now at the time. of the technology in form of a regulates the pulse time for the LED calibration procedure when the LEDs with the lowest current, here LED1, to The significant reduction in power are switched on for the first time. approximately 90 percent of the period consumption contributes to the higher Within this calibration procedure, the duration of 2.048 ms. This LED1 flexibility of your application. Thanks to current in each channel is measured, operates at a frequency of the independent control of every LED, and the value integrated and close to 500 Hz. the use of Buck converters is possible: compared to an internal reference. They work with an efficiency of up to Then the time until the measured value Calculating the corresponding on-time 95 percent, much more efficient than is equal to the internal reference is for LED2 would mean that this LED the present Boost converters. The counted. The LED-channel with the with a double current will only get an proportion of the energy consumed by lowest current will be to a duty cycle of on-time half of LED1 (0.5 * 2.048 ms * the LED control sinks from 10 or 15 D = 0.9, whereby the pulse times of 0.9). Additionally, to prevent flickering percent to under 2 percent. This is not the other channels refer to this value. LEDs, the period time is cut in half and just the requirement for implementing When the equivalent value is reached, instead of one pulse the LED2 will be LED in mobile applications that use the the controller switches the channel off pulsed twice in one period time of majority of their energy for lighting – for until the next sequence starts. To see LED1. This LED operates at example a notebook with a TFT this in an exemplary case makes this approximately 1000 Hz. display- but is also advantageous for more comprehensive: off-line lighting systems. Even a In the same way, the pulse time for portable projector, which gets its Figure 2: LED3 is determined. Compared to power completely from batteries, Parallel arrangement of LED1 it has four times the current, thus becomes reality. Altogether, this new three LED ( LED 1: it will be given only a quarter of the technology significantly widens the high Vf - д If1 = 150 on-time of LED1. Again, the period application possibilities for high mA, LED 2: avg. time of LED3 is also only a quarter of brightness LEDs: The spectrum V - д I = 300 mA f f2 LED1. LED3 will be pulsed four times reaches from industrial visual and LED 3: low during the on-time of LED1. LED3 inspections with the highest Vf - д If3 = 600 mA) operates at around 2000 Hz. requirements of precision up to the Figure 3: automotive industry, which demands Controller signal for LED 1 The charge through each LED is product reliability under challenging exactly the same, which results in an environmental conditions. homogeneous appearance in colour and luminous flux. Saving Time and Money With this technology, driver Unrivalled Flexibility modifications can be – for the first time All the advantages of this new driving – completely realized through Figure 4: principle were made easyily applicable software. The vastly shortened time to Controller signal for LED 2 by a LED-driver component, the market guarantees crucial competitive DIL16CL01 ASIC. advantages. Through the development of new LED controls, optimization Thanks to the precise and efficient potential exists in many enterprises. controls, as well as clearly lowered Typically, an internal development energy consumption, this approach department is assigned to conceive a opens new horizons to the driver for special purposes. They order Figure 5: manufacturers of LED applications. By the necessary hardware (for example Controller signal for LED 3 deploying this technology with the prefabricated driver chips) and create DIL16CL01, LED-applications become an experimental set-up that will more dynamic. Users may determine subsequently run an iteration of tests, to the microsecond exactly where light which will in turn lead to a prototype of is needed. Where no light is necessary, the driver electronic. This process is energy will be cut off – this provides handicapped by the limited possibility time for thermal relief. The control of of electronic and thermal simulation the lighting applications in interaction and the common deficient

documentation of the hardware. Conclusions Only when the driver electronics Charge controlled systems are is functional, can the real not completely new in the development begin. In particular electronic industry. But it has the thermal design of the never before been made application requires the applicable this easy for LED- availability of the LED as early as systems. Coming from possible. Speeding up this conventional driving methods, process, requires the constant current, constant development of environments voltage and PWM, this that contain all the components technology opens the doors for for the handling of high- applications which remained out performance LEDs in multi- of reach for technical or channel applications. Creating economical reasons. The applications with 80, 128 or more tremendous reduction of complex LED-channels became very easy. electrical designs of multi- channel applications is an A further fundamental advantage evolutionary step in LED-driver of this approach is the dynamic technology. development process. Instead of developing a new driver for every The way of working with LEDs application, necessary changes in a way where users modifications are fully realized understood the control of the through the software. The forward current as the key- companies can react immediately parameter in LED driving and will to changing requests and adapt now learn that current is actually the driver commodity to new less important than charge, at applications. For applications that least in pulsed applications. should feature more driver Furthermore, the possibility of algorithms or are supposed to making LED driver hardware interact with sensors, free designs work in different resources in the controller and applications simply by memory are available – the cost implementing application specific and expenditure of time for the software is the second way that integration of external will change the way of working components are omitted. This with LED. concept puts users in the position to bring new products to the controLED-technology, market quickly, flexibly and implemented in the DIL16CL01 economically. pushes the boundaries further out, enabling simple designs but precise control of LEDs. It makes high-power multi-channel applications cheap, creating new ideas about what can be realized with LEDs in any part of life.

ELECTRONICS LED POWER SUPPLIES 60

Needed Accuracy of an LED Power Supply

High quality LED drivers are mandatory for today's LED lighting applications. There is no doubt that current control accuracy is important but the output that truly matters is light. Christopher Richardson, Systems Applications Engineer for Lighting at National Semiconductors, discusses how accurate the current control has to be, and shows what would be the best solution for making the most of every cent invested in LED power supplies.

LED technology for general best to coordinate efforts from experts ever tighter control to prevent high illumination has reached a point in the other areas. The system rates of bit error. As a result, tolerances where high quality lamps are engineer often brings old habits from for digital power supply rails are possible, but building a high their area of expertise into the design. commonly controlled to within ±1% or quality LED fixture requires A similar phenomenon can occur when less of their nominal value, or are knowledge of power electronics, an electronics engineer with a focus on specified in absolute terms, i.e. 0.99V optics, and thermal management. digital systems is faced with power to 1.01V. The problem with applying Few engineers possess expertise management: they may rely on pure this habit from traditional power in all three fields, and when the simulation and spin a PCB without lab supplies to the field of LED drivers is power supply engineer is also the testing their power supplies, not that tight tolerances of output current system architect, there can be an realizing that switching regulators require more power to be wasted, undue focus on the accuracy of require careful attention to PCB layout more expensive components, or both. output current. There is no doubt and cannot be trusted to behave as that accuracy is important, but the simulators predict without bench Making Every Penny Count when the final product is a lamp, testing. The ideal power supply costs nothing, the output that truly matters is has 100% efficiency, and occupies no light. This article explores a focus In the design of an LED lamp, when space at all. Power electronics on tight control over LED drive the system architect is the power engineers are used to hearing this from current which can inflate the cost electronics expert or when the power their customers, and they make the of the LED power supply, when in supply design is contracted to an best of these demands by designing fact it is light output that really engineering firm some habits common the system with the best efficiency in matters. Closing the control loop to standard power supply design can the smallest space while using the on actual light output is creep into the LED drive. Some such budget they are given. LED drivers are presented as the best option for habits are beneficial, and in many no exception, and in fact, are pressed making the most of every cent respects an LED driver is quite similar particularly hard in terms of budget invested in LED power supplies. to a conventional, constant-voltage because conventional lighting power supply. Both types of circuits technology is fully commoditized and Introduction operate from a wide range of input very affordable. Therefore, it is The emerging field of semiconductor voltages and over wide ranges of extremely important to make the best lighting is creating a demand for output power. Both types of circuits use of every penny allotted. This is engineers with expertise in three main face challenges depending upon their where some power electronics fields: power electronics, optics, and connection to AC mains, to regulated designers are led astray by those old thermal management (mechanical DC rails or to batteries. One habit of habits. Controlling an LED current to engineering). Currently there aren’t too power electronics engineers that isn’t the same accuracy as the supply many engineers with experience in all always so helpful for LED drives is the voltage of a digital load wastes power three fields, and this often means that desire for high accuracy of the output and money. Assuming that the the system engineer or overall product – voltage or current. Digital loads like currents in question range from 0.1 A engineer comes from a background in FPGAs and DSPs require ever lower to 1A covers the majority of designs one of these fields and must do their core voltages which in turn require being released today, especially

Figure 1 (left): Voltage feedback (a) and current feedback (b)

Figure 2 (right): Optical integrating sphere in cross- section

Table 1: Luminous Flux Luminous Flux Luminous flux Tolerance of Lowest Tolerance of Averaged Tolerance Manufacturer Range of Lowest Bin Range of Highest Bin bins for cool white Bin (%±) Highest Bin (%±) of All Bins (%±) (lumens) (lumens) LEDs tested at 350 mA and at 25ºC A 114 to 122 3.39 139 to 148 3.14 3.26

B 40 to 50 11.11 100 to 120 9.09 10.10

C 89.2 to 97 4.19 112 to 121 3.86 4.03

considering that 350 mA (or, more less power dissipation, which also engineer then reasons that a highly precisely, a current density of 350 mA meant smaller, cheaper, lower power accurate current is needed. In doing per square millimeter of opto- current sense resistors. In a simple so, they forget that lumens and lux, not semiconductor junction) has become a case with low-side feedback -- as amperes, are the outputs that truly common compromise between shown in Figure 1b -- 200 mV was a matter. Amperes are easy to measure. thermal management and luminous common choice. Expecting a tolerance Light, on the other hand, requires efficacy. The ICs that control LED of ±1% from a 200 mV reference, expensive, bulky equipment such as drivers are silicon based and therefore however, is an invitation for an the integrating sphere (Figure 2) which have a typical band gap in the range of overpriced IC. This translates to a is not a familiar instrument to most 1.25V. To achieve a tolerance of 1% at tolerance of just 2 mV above and 2 mV electronics engineers. 1.25V requires a range of ±12.5 mV. below the nominal reference voltage. This is not difficult to achieve, and While not impossible, the higher What’s more, even a current source affordable voltage references or power precision does not come for free. with a tolerance of ±0.1%, (which supply control ICs that boast such a A ±2 mV tolerance would likely require would be quite expensive) would have tolerance or better are both plentiful production, testing and binning plenty of marketing value but little use and affordable. When controlling techniques reserved for high precision in producing tight tolerance of actual output voltage, high precision resistors voltage references. The added cost light output. This can be confirmed by can be used to feed back the output would be much better spent on more observing the binning of luminous flux voltage while dissipating very little intelligent LED drivers. One particular for the LEDs. Table 1 shows the power (Figure 1a). To control output feature that is worth the added cost is luminous flux bins for cool white LEDs current requires a change in feedback an additional feedback loop that allows tested at 350 mA and at 25ºC for method as shown in Figure 1b. This is light output, not current output, to top-grade LEDs from the top three of by no means the only way to control determine how the LEDs are driven. the world’s power opto-semiconductor output current, but it is the simplest. manufacturers. Note that the final Measuring Light Output column is the average of the tolerances Upon further inspection a principal Just as the digital designer looks to of the individual bins, not the tolerance disadvantage becomes evident: the simulation when faced with the across all the luminous flux bins. load and the feedback circuit are one uncertain territory of power supply and the same. The reference voltage is design, so the power electrics Calculating Light Output applied across a resistor in series with engineer turned-System Architect may Accuracy the LEDs, and this means that the go for the familiarity of high accuracy Knowing that the LED´s light output higher the reference voltage or the LED outputs when faced with an LED lamp from a single flux bin has a tolerance current the greater the power design. LED manufacturers have made ranging from ±3% to ±10% might lead dissipated in that resistor. As a result, it clear that luminous flux is the system engineer to conclude that the first generation of dedicated LED proportional to forward current. Drive drive current tolerance must indeed be drive ICs had much lower voltage all the LEDs with the same current, as tight as possible, but from a references, similar to those found in and each one should produce the statistical viewpoint this is not correct. battery chargers. Lower voltage meant same flux. The power electronics A common but incorrect assumption

Table 2: Current Source Overall Tolerance with Overall Tolerance with Overall Tolerance Overall tolerances Quality LED Lamps have Tolerance (%±) A (%±) B (%±) with C (%±) vs. a list of more Feedback hypothetical 0.1 3.26 10.10 4.03 LED manufacturers and their current source 0.2 3.26 10.10 4.03 distribution partners are working hard tolerances to improve the tolerance of luminous 0.5 3.27 10.10 4.04 flux for their products and to provide 1 3.30 10.11 4.06 narrower bins at reasonable cost. For 2 3.41 10.15 4.15 designers who want to build a high 5 4.11 10.40 4.74 quality product capable of lasting five 10 5.97 11.27 6.42 years or for 50,000 hours and maintain the total light output over that time, even the tightest flux binning and the Figure 3: mythical 0.1% tolerance current source Overall light output tolerances simply will not suffice. This is because vs. current source two important factors reduce the flux tolerances from LEDs that cannot be accounted for even if the current source tolerance and LED flux tolerances were each 0.001%: heat and time-based degradation. To account for these loss terms designers of quality solid-state lighting products must look to power supplies with additional feedback loops, namely heat and light itself. For these purposes dimming control is needed, and control ICs with the ability to adjust output current both linearly and with PWM are the best equipped.

Table 3: Flux Flux Flux Tolerance of the Flux Flux Flux Two Driver Examples for Tolerance Tolerance Tolerance LED´s light output Range of Range of Range of Everything else Manufacturer of Top of Top of Top Top Two Top Three Top Four The LM3409 and LM3424 are LED Two Bins Three Bins Four Bins Bins (lm) Bins (lm) Bins (lm) (%±) (%±) (%±) driver control ICs which represent the second generation of current sources 130 to 122 to 114 to A 6.5 9.6 13 for semiconductor lighting. Both offer 148 148 148 control over average LED current via 90 to 80 to 70 to B 14 20 26 variable resistors or voltage sources, 120 120 120 and both offer dedicated inputs for 104 to 97 to 89 to PWM dimming signals. In addition to C 7.6 11 15 121 121 121 enabling linear control loops, the analog adjust functions of the LM3409 and LM3424 also allow the system for overall tolerance of any value of When Equation 1 is evaluated it shows designer to make their own decision interest is that the worst-case values that the factor with the worst tolerance when trading off output current simply sum. The tolerance of the dominates the others, and also that the accuracy for size, cost, and power current source powering the LEDs and true overall tolerance is significantly dissipation in the current sense the tolerance of the flux from the LEDs better than the sum of the worst cases resistors. are uncorrelated – they vary of the individual factors, especially independently of one another on a first when one factor is much greater than The LM3409/09HV, shown in Figure 4, order basis. For uncorrelated two the others. Observing the graph in controls buck circuits, the most factors X and Y, the overall tolerance, Figure 3, a more reasonable target for common type used in power LED Z, is not the sum of the tolerances of X current source tolerance would be in drivers. The LM3424 is shown in and Y. It can be calculated with the the range of the tolerance of the LED´s Figure 5 as a boost regulator LED following expression: light output. Keeping in mind that for driver but is also capable of buck- cost purposes many lamps use LEDs boost, SEPIC, flyback and even from several bins, the tolerances for ´floating´ buck circuits. (1) the top two, top three, and top four luminous flux bins for the same LEDs as those of Table 1 have been listed in Table 3 for reference.

Figure 4: Typical schematic Applications that Deserve Light Control of LM3409/09HV Street lighting is a good example of a light source that is buck LED driver tightly bound by legal standards. For public highways, countries in the European Union define the minimum and maximum light output and the illumination pattern. For an LED streetlight to provide lighting that is within the specifications over five years or even longer, the design must take into account the immediate loss of luminous flux due to heat and the long-term loss of flux due to degradation over time. One natural choice is a light sensor such as a photodiode that forms a linear control loop. On Day 1 the system should be designed to use some fraction of the total available drive current, with the expectation that over time the drive current will increase up to a defined limit, keeping light output constant. The photodiode could be biased and converted into a pulse width modulation signal, which would help maintain a more consistent correlated Figure 5: color temperature over the dimming range, but linear control LM3424 boost LED driver loops are simpler and in general the dimming range is fairly small. PWM control would be of more use in controlling light output based on time of day, motion sensors, or other power-saving measures. Figure 6 shows a hypothetical block diagram of an LED lamp designed for long life and consistent light output over that long life. Conclusion The true measure of an LED driver is partly the accuracy of the output current, but while the tolerance of the luminous flux from the LED themselves remains significantly higher than ±1%, there is little point in a current source with a tolerance as tight as a voltage rail for digital processors. Average LED current tolerance should be more or less equal to the tolerance of luminous flux. This article has shown the ideal case, using the tolerance from a single bin, as well as more practical cases with LED lamp designs that use LEDs from two or more flux bins and tolerance could easily be ±5%, ±10% or more. The money that would be spent on 1% Figure 6: current control and the power that would be spent in greater PWM for day/night control, linear sensing voltages could both be put to better use in control for light additional control loops. Some LED lamps will choose output simplicity and low cost, where even linear dimming is too complicated and costly, but those lamps designed to take full advantage of LED’s potential will use linear, PWM or a combination of both dimming methods to maximize performance and lifetime.

Imprint

LED professional Review (LpR) ISSN 1993-890X

Publisher Luger Research e.U. Institute for Innovation & Technology phone +43 5572 394 489 dep. LED professional fax +43 5572 394 489 90 Faerbergasse 15, Haus Rot [email protected] A 6850 Dornbirn, Austria / Europe www.led-professional.com

Publishing Editors Siegfried Luger phone +43 5572 394 489 Arno Grabher-Meyer phone +43 5572 394 489-18 [email protected]

Int. Account Manager Theresa Koenig phone +43 5572 394 489-20 [email protected] LED professional Review (LpR) - Annual Subscriptions

LpR Digital Magazine Front-page picture • 6 issues Image: Arno Grabher-Meyer, LED professional, eldoLED Powerdriver • pdf download Artwork: Thomas Klobassa, ©LED professional 2011 • high resolution pictures and graphs • printable • commercial use Copyrights – Luger Research e.U. • access to all previous issues The editors make every reasonable effort to verify the information published, • Euro 78.80 but Luger Research e.U. assumes no responsibility for the validity of any http://www.led-professional.com/subscription manufacturers, non profit organisations or individuals claims or statements. Luger Research e.U. does not assume and hereby disclaims any liability to any LpR Printed Magazine person for any loss or damage caused by errors or omissions in the material • 6 issues contained herein, regardless of whether such errors result from negligence, ac- • Euro 158.40 cident or any other cause whatsoever. You may not copy, reproduce, republish, download, post, broadcast, transmit, make available to the public, or otherwise Next LpR Issue - March/April 2011 use LED professional Review (LpR) content without prior written consent from LED Testing, Simulation & Manufacturing Luger Research e.U. – Institute for Innovation & Technology, Austria.

LED Lighting Technologies 27-29 September 2011 | Festspielhaus Bregenz | AUSTRIA

FOR DETAILED INFORMATION ON SPONSORSHIP & EXHIBITION OPPORTUNITIES PLEASE CONTACT US: Ms. Theresa Koenig | +43 5572 394489 20 | [email protected] WWW.LED-PROFESSIONAL-SYMPOSIUM.COM | [email protected]

e o

—

i —

g E

h r

t s

i v i n n g

L g i g h t i n rand S g b P r h o b Platform d usiness2 withour Company’s u b b y a c d ts our Enhance — y — n L share ig etwork h ccelerate n g ti a n your Marketbusiness g China's One-stop LE h sy Expand your st — a em Extend s — i /P V s E ola s x r Ce ion lls— olut p Ligh al s o ting appl ns—Therm a icatio 11 nd Forum 20

i ngha x sha May 11~13, 2011 — inte

OrganisEd by

www.greenlightingchina.com For the Exhibition Miss Selina Wang, Tel: +86 21 5153 5110, [email protected] For the Forum Miss Betty Xu, Tel: +86 10 5172 7115 [email protected] For Media Miss Sonia Xia Tel: +86 21 5153 5178, [email protected]