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Review LpR The leading worldwide authority for LED lighting technology information May/June 2011 | Issue 25

LED Street Lighting DC-Microgrids LED Signage Driver Thermal Management LED Investor Forum THE LATEST AND GREATEST LED LIGHTING

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49714_Illumination_MAY ADV_P6.indd 1 20/04/2011 12:55 EDITORIAL 1

A Guideline for Street Lighting

As an emerging technology, LED street lights have yet to experience major market penetration. On the other hand, cost reductions and performance improvements are continuing to increase LED street lighting viability. Lighting, energy, and economic performance will all be important factors in LED street lighting developments.

The high initial cost of LED street lights has been a challenge, but energy savings and projected maintenance cost savings through the luminaire lifetime both improve LED street light economics. Recent studies showed energy reductions ranging from 50% to 70% over current HPS systems.

But there are some legal, technological and application questions that arise with the use of LEDs for street lighting. These questions have to be carefully considered when entering this segment of the market. LED professional had the chance to speak with Prof. Tran Quoc Khanh, who is a professor at the University in Darmstadt, Germany and one of the leading street lighting experts, worldwide.

We explored the following topics: What is the legal situation in regards to the existing standards? Can we save additional energy with LED lights due to the differences between the mesopic and the scotopic viability? What has been identified when using pulsed LED light in traffic applications? How should an intelligent LED street light be designed? What are the boundaries for the use of solar-powered street-lights and are hybrid systems the future?

The answers from Professor Khanh were surprising and I’m sure his insights into the topic of street-lighting will serve as a useful guideline for your own thoughts and product concepts for the street-lighting market.

The LED professional Symposium +Expo 2011 (27-29 Sept.) is really gaining momentum. First class presentations will provide you with new insights into LED lighting. You will meet the Leaders in LED lighting in an extraordinary exhibition area in the Bregenzer Festspielhaus (James Bond film location) and you will be able to discuss your topics with the experts. A great chance to build and expand your networks! Take advantage of the Early Bird bonus and reserve your ticket now. We are very excited about the chance of meeting you personally in Bregenz and supporting you with winning approaches in LED lighting.

The complete program is available now at www.lps2011.com for downloading.

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

Farnell C2

Editorial p 1 COMMENTARY p 4 LED professional Symposium p 3 Imprint p 60 News - PROJECTS p 5 News - PRODUCTS p 6 Lambda Research p 7 News - RESEARCH p 21 CORRECTION p 24 Toshiba p 9

LEDLink p 11

EVENT Everlight p 13 LED Investor Forum 2011 - Santa Clara p 26 by Alan R. Miles, LED professional Instrument Systems p 15

Edison p 19 INTERVIEW LED Street Lighting - p 30 Signcomplex p 23 About Standards, Challenges and Misconceptions Interview with Prof. Tran Quoc Khanh, TU Darmstadt Willighting p 24 by Siegfried Luger and Arno Grabher-Meyer, LED professional Recom p 25

APPLICATION Vossloh-Schwabe p 27 DC Microgrids and SSL - p 34 Key Components for Zero Net Energy Buildings Carclo p 29 by Brian T. Patterson, EMerge Alliance and Karen Lee, Osram Sylvania Macroblock p 29

ELECTRONICS p 40 Osram p 33 LED Driver Innovations for High-Performance Signage by Roland Gehrmann, Toshiba Consumer & Industrial ICs Kingbright Electronic Europe p 37

Taitronics p 39 THERMAL LED Cooling in Harsh Environments with Synthetic Jet Technology p 44 Fischer Elektronik p 41 by Markus Schwickert and Brandon Noska, Nuventix Micrel p 43 Thermal Management of LED Lamps p 48 by A.Motoya, M. Kai, Y. Manabe and S.Shida, Panasonic Corp. OLED Lighting Design Summit p 49

Curamik p 51 SPECIAL TOPICS HB-LED Alert Device with Intense Light Output p 54 euroLED p 53 by Jerry Vereen, Egret Technologies NEPCON Malaysia p 53

LED light for you p 55

Infineon p 58

Lighting Fair Korea p 59

Philips-Lumileds C3

CREE C4

EARLY BIRD BONUS SIGN UP NOW! www.lps2011.com LED Lighting Technologies International Winning Approaches

APPLICATION OF LED Another, different example for the implementation oriented use of LED TECHNOLOGY technology is the utilization of chips with a CRI value of 98 and more. This guarantees the best possible color LED technology creates new potential rendering of works of art in museums, for product designs as well as the use galleries and cultural buildings. of light for interior and outdoor architecture. Lenses that have been calculated exactly, project focussed light on the LED technology is a guarantee for work plane. “Light for Industry and resource conservation not only in Technology” increases productivity energy consumption but also the and guarantees safety as well as using up of fossil fuels. creating an attractive work place.

Herbert Resch Technologically, it seems like what is The application of high efficiency Lighting Expert, Founder possible is continuously increasing. LEDs with precisely calculated lenses The LED lumen/watt has reached the also minimize light smog and in some and Business Manager of values of fluorescent lamps, and has, cases even eliminate it completely. Symetrys in some cases, even surpassed them. Color rendering (CRI) is at 98+, Who hasn’t been bothered by almost the same as a tungsten “blinding” lanterns that shine into the halogen lamp. Dimming LEDs without living room or bedroom and interfere the color temperature changing is a with perception as well as causing standard, just like the generation of aggravating glare? any imaginable light color by steering RGB model LEDs. Intelligent LED systems create atmospheres in offices, schools and I think it is important, though, that hospitals with technology that allows new light and control system for steering the color temperature developments are oriented on from 2800 K to 6600 K. implementation. Technology is defined by implementation and not The quality of light is an important the other way around. part of the quality of life. In the future, technological LED technologies make it possible to developments will allow innovative create small, elegant light systems for manufacturer systems to steer: use indoors as well as outside. We often see LED technologies integrated • Light direction (spot and flood) into outdated light housing in order to • Light color (2800 K - 6600 K and save the costs for tools needed to the color spectrum) develop new design vocabulary. Not • Light intensity only is the aesthetic value lost, but also the advantages of miniaturization from one place. However, people will and/or resource optimization is not still be needed to choreograph taken into consideration. architecture and space.

In this way, for example, the smallest Ettorre Sottsass: high efficiency spotlights and wall LIGHT NOT ONLY ILLUMINATES, IT washer systems for presentations and TELLS A STORY. LIGHT IMPARTS sales can be developed. Because MEANING, ILLUSTRATES LEDs don’t generate any radiant heat, METAPHORS AND CREATES THE they are ideal if you don’t want to STAGE FOR THE COMEDY OF LIFE. damage the exclusive materials in a LIGHT ALSO TELLS THE STORY OF boutique. ARCHITECTURE.

H.R.

The Christopher Lumenal Brings Evans Goldsmiths in Poynton features New Sparkle to Lumenal’s LED ceiling recessed Sol lamps Christopher Evans and Sirius strip lights Goldsmiths

Lumenal has fitted out jewelers Christopher Evans Goldsmiths in Poynton, Cheshire, with its premium quality LED lighting solutions to enhance the shelf appeal of merchandise on display. The Sirius strip lights and ceiling recessed Sol lamps were chosen as a more effective, durable and longer lasting alternative to conventional display lighting options.

The largest benefits A further advantage offered by Lumenal’s for this jewelry retailer are the quality of light lamps is their energy efficiency. They typically output and the more require 30-40% less energy than conventional comfortable store fittings while providing the same or improved environment thanks quality of light. This results in considerable to the lack of heat savings in energy costs, which, in combination with the loss of maintenance costs, will provide Christopher Evans Goldsmiths a return on investment within 24-30 months.

Proprietor and chief goldsmith, Christopher Evans, comments on the success of the fit out: “There are two benefits in particular that have come from installing Lumenal’s LED

The Christopher The flexible nature of LED lighting allowed Evans Goldsmiths Lumenal’s expert engineers to manipulate the in Poynton is now color of light emitted by their strip lights to benefiting from the ensure optimum illumination of the various high performance of metals and gemstones on display within each Lumenal’s LED lights of the store’s wall recessed and counter unit display cases. Warm white light was incorporated to make gold items appear lustrous, as well as neutral white light, which optimizes the appearance of silver and diamonds.

The superior diodes used within Lumenal’s products will guarantee the consistency of the specially designed light colors, as well as Lumenal’s lighting produces little heat, brightness, throughout the lifetime of the removing the problem of an uncomfortably lighting. One is the quality of the light emitted fittings, which is expected to be in excess of warm store environment, often experienced by the fittings. They are far brighter than the 50,000 hours constant use. This remarkable with conventional lighting, which usually emits conventional lights we had previously, and lifespan, which is roughly equivalent to 10 a much larger amount of heat. This also certainly bring our diamonds to life.” years, assuming 85 hours trading per week, is means that the store’s jewels will stay cool to a result of the fittings’ expert design the touch, making them more appealing to “Second, our main problem with the previous combined with their inherent resistance to customers when handled. Lumenal’s LED lighting was the amount of heat they emitted, shocks and vibrations. Their robustness lights also remove the risk of packaging and which made the closed shop environment eliminates the maintenance costs of replacing display materials caused by ultra-violet light, very uncomfortable for staff and customers, blown bulbs as well as the inconvenience of which is emitted by conventional sources, but and incurred considerable running costs due less effectively merchandised displays not LED lighting. to air conditioning requirements. As Lumenal’s because of poorly illuminated cabinets. LED lighting emits significantly less heat, these problems no longer exist for us.”

ZEMOS LED Comes to 80,000 hours on applicable models that consistency with real-world 85°C implement our ZemosLED Power Package. specifications. Creating a design with Up with New Other models in our line of products have a CXA2011 was simple and manufacturing will Patented ZEMOS minimum life span of 50,000 hours. be underway in record time.” 9090 Package for • ZemosLED only uses materials that are “Combining fast and flexible system design 100% eco-friendly. with ease-of-manufacturing, the CXA2011 Extreme Capabilities • They contain NO mercury or other LED array helps customers quickly create a Patented in 2009, the ZemosLED Power hazardous materials which require proper broad range of LED-based designs,” said Package uses advances in technology to disposal. Mike Watson, Cree senior director of significantly increase the life span of LEDs, the marketing, LED components. “Lower system most energy efficient and longest lasting light The Zemos9090 package disperses heat in cost and quicker time-to-market are keys to source available. A result of three years of the most effective manner to prevent a accelerating the LED lighting revolution.” intense research and development by our sudden rise in Junction temperature. engineers with over 20 years of LED ZemosLED is able to achieve this through experience, the ZemosLED Power Package state of the art thermal design of the LED has unprecedented thermal management package. Unlike conventional LED package capabilities. structures that use a combination of an Epoxy resin cover and a thin copper slug, the entire substrate of the Zemos9090 package is pure, thermally-conductive copper. Therefore, Zemos9090 products disperse heat fast and efficiently, keeping junction temperatures steady. Cree’s new CXA2011 LED array helps to reduce system cost, to speed time-to-market and to simplify fixture and lamp design Various tests, performed in different environmental settings, have demonstrated Features: that it generally takes tens of thousands of • Available in ANSI white bins as well as hours for Zemos9090 LEDs to lose 30% of 4-step and 2-step EasyWhite bins at their Lumen output. Zemos9090’s 2,700K, 3,000K, 3,500K, 4,000K, 5,000K The new ZEMOS 9090 is a versatile high quality revolutionary thermal and optical designs • Forward Voltage: 40 V 3W white LED package easily meet LM80 test criteria. ZemosLED will • 85°C binning and characterization Features: soon publish LM-79 and LM-80 test results, • NEMA SSL-3 2011 standard flux bins • Proprietary solid copper package with silver along with EnergyStar certifications. • Max drive current: 1,000 mA plating. • 120° viewing angle, uniform chromaticity • High luminous flux, up to 130 lm/W • Top-side solder connections • Low thermal resistance of just 5 K/W • Thermocouple attach point • Large 9mm x 9mm area effectively Cree Delivers • Screw down attachment dissipates heat into underlying PCB • RoHS and REACH-compliant • Non-protruding lens of low viscosity silicon Brightest and Most- • Unlimited shelf life at is less susceptible to damage, and puts Efficient Lighting- ≤ 30°C/85% RH less stress on bonding wires. • Reflow solderable Class LED Array Easy-to-use screw-mounts simplify the • Available CRIs of 65 to 95 Cree, Inc., a market leader in LED lighting, manufacturing and design process by • Maximum recommended drive current of announces full availability of the industry’s first eliminating the need for complex design- 1000 mA lighting-class LED array that help reduce specific engineering and reflow soldering. • SiC based LED substrate overall system cost by combining superior With the CXA2011, Cree leads the way on • Lifespan of up to 80,000 h with proper heat efficacy, ease-of-design and ease-of- color accuracy by extending the industry’s sinking manufacture. The Cree XLamp® CXA2011 largest offering of LEDs characterized at LED array is designed to deliver the smooth real-world operating temperatures (85°C). We rigorously test 100% of our power light output and consistent color needed for package products for a minimum of 72 hours. applications such as omnidirectional bulbs or The CXA2011 LED array delivers up to 4,000 Our unique testing process includes boiling directional downlights. lumens at an operating temperature of 85°C Zemos 9090 packages in an ink solution (1A, 5,000 K) in a single component. It is where defective LEDs are identified and “The CXA2011 LED has been incredibly easy available in 2-step and 4-step EasyWhite™ discarded. This protocol eliminates any to work with, enabling us to create very options, delivering the industry’s tightest chance of leakage due to humidity and high-performance products,” said Jason Lee, LED-to-LED color consistency—reducing moisture that can penetrate other LEDs. president of Gama Illuminer. “It gave us a system complexity and making light source As a result of stringent testing and superior plug-and-play solution with the right selection as easy as specifying a color quality, we ensure our LED’s performance up combination of brightness, efficacy and color temperature.

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New LUXEON H LED: available, 2700K and 3000K, with typical CRIs Verbatim Launches of 83. Typical flux is 84 lumens and 90 lumens High Voltage LED respectively for the two correlated color Color Tunable OLED temperatures. The new LUXEON H emitters Uses Rectified AC are identical in footprint to the compact Lighting Philips Lumileds, a LED technology and LUXEON Rebel and LUXEON Rebel ES LEDs Verbatim has launched the world’s first market leader, continues to expand its further simplifying implementation. commercially available, color tunable organic LUXEON LED portfolio with its first high LED (OLED) lighting panels at the Fuori Salone voltage emitter, LUXEON H. The new emitters “Our thin film flip chip technology allows us to show in Milan. The OLEDs are based on are driven directly with rectified AC voltage continue to develop innovative solutions, like unique materials technology developed by rather than constant DC current. This high the multi-junction die in LUXEON H, for the Verbatim’s parent company, Mitsubishi voltage architecture maximizes space for illumination market,” said Frank Harder, VP of Chemical Holding Group which, as one of the additional thermal management, permitting an Product Marketing for LUXEON. “The base of world’s major chemical companies, has over increase in the thermal limit for even the some bulbs is so small that it’s impossible to 50 years’ experience in developing lighting smallest bulbs. The 50 Volt LUXEON H flexibly fit both an electronic driver and a heat sink in materials. Full-scale production of OLED supports both 110 V and 240 V solutions. the space. LUXEON H only requires a bridge panels will start in July. rectifier and a resistor, both of which are very small, and the remaining space can be used Verbatim demonstrated the creativity and for thermal management. And, because we beauty of color tunable and white tone don’t use direct red die like most other HV tunable OLED panels, thought to be the solutions, LUXEON H offers consistent, stable world’s largest at approximately 14 cm x color from the instant the LED is powered and 14 cm. Its display, created by lighting designer maintains its color through its lifetime.” Satoshi Uchihara, was located in the Design Library srl, Via Savona 11, 20144 Milan. Initial uses of LUXEON H are expected in the With the small footprint LUXEON H, Lumileds retrofit bulb market where form factors for the The large surfaces of Verbatim OLEDs, enters the high voltage LED market bulbs are already defined and space is at a branded VELVE, produce a soft light, free premium—especially so for the smallest bulb from glare and with deeply saturated colors. Features: types ranging from the candelabra to the The OLEDs, which do not contain hazardous • High voltage architecture maximizes space intermediate Edison, E10-E17 types. Philips materials, are very efficient, producing 28 for thermal management Lumileds expects new solutions using lumens per Watt output at 1000 cd/m2 with • Requires only a bridge rectifier and resistor, LUXEON H to come to market during the accurate color rendering (high CRI). Color no DC driver second quarter of the year. tuning and white tone tuning allow the mood • ANSI compliant binning at CCTs of 2700 K and 3000 K Verbatim’s color • Exceptional color stability over temperature changing OLED desk and color current lamps at the Fuori Salone - Milan 2011 • 50 V emitter supports 110 V and 230 V solutions • Exceeds ENERGY STAR lumen maintenance requirements

Benefits: • Simplified solution for space constrained implementations • Lower system costs • High quality of light • Exceptional color stability over temperature for real-world application performance and reliability • High efficacy for sustainable lighting design of a space to be varied to suit its function at • Complete optical, electrical and mechanical the time. For example, it may be changed design resources help you get to market from a workspace requiring bright, cool light, faster to a place of relaxation with warm, subdued lighting. Designed to meet the demands of space constrained retrofit bulbs, LUXEON H emitters The panels are designed for general lighting, deliver industry leading thermal performance Verbatim’s color changing OLEDs showing the furniture lighting and other applications. and reliability as well as high quality, warm color tuning capabilities Verbatim sells the OLEDs directly to original white light. Two color temperatures are equipment manufacturers (OEMs).

WE’RE CREATING A BRIGHTER FUTURE FOR EVERYONE.

At Toshiba we make bright brighter with innovative products offering lower power consumption, longer operating life and a more compact form factor. Our new range of high luminous flux transparent white LEDs achieve luminous efficacy values of 120 lm/W, and with a height of just 0.65mm, they are one of the industry’s thinnest packages. With our full line up of high efficiency, high output and high color rendering models, lighting designers in commercial, residential and industrial applications can contribute to reducing CO2 emissions and making the future brighter. Visit us today at www.toshiba-components.com/LEDS

To simplify development work, Verbatim offers Gaggione: Color two products. A sample kit for architects, lighting designers and planners and Mixing Collimators for development engineers contains an OLED that can be connected directly to the mains. It OSTAR SMT can be used to evaluate seven pre- The highly efficient product line of 45mm programmed saturated colors, white tone diameter collimators provides excellent color tunability and a dimming function. Software mixing properties to address stage lighting, control is implemented over a USB entertainment lighting architectural lighting connection. The second product is an OLED application, and other applications looking for module with a printed circuit board that Philips Lighting extended its range of LED power and intensity with excellent cut-off and provides an industry-standard DMX interface spotlighting modules for the retail sector, with light efficiencies. for RGB color control and a DALI interface for the introduction of the Fortimo LED SLM 3000 white tunability. Fields of Application: Delivering 3,000 Lumen at more than 70 lm/W • Stage lighting The OLED sample kit will be available in May and a CRI above 80, the Fortimo LED SLM • Entertainment lighting 2011, and the OLED module during the 3000 combines reduced energy use with the • Architectural lighting second half of the year. highest levels of crisp white light from a LED • Floodlight for shop lighting lamp, as well as unmatched flexibility in its • Scientific/Instrumentation class. With no re-lamping required, the Fortimo • Signaling/Industrial LED SLM 3000 also paves the way for Philips Introduces minimum-maintenance lighting. And since it is Benefits: fully InGaN-based technology, this LED • Light output efficiency up to 90% Fortimo LED SLM spotlight module meets the toughest demands • Excellent color mixing property for stable white light, a key requirement in • Sharp cut off with very narrow beam 3000 Module accent lighting for modern retail outlets. • ZOOM alternative with secondary lens As well as a lifelong consistency of color temperature, the Fortimo LED SLM 3000 Several beams with gives retailers new levels of freedom in display high output ratio options. Closer illumination is now possible, are available : 7.5°, thanks to reduced levels of UV and IR, and 21°, 35°, 7.5°x37° as highly accurate dimmability (down to 10%) well as a zoomable enables more creative and dynamic displays. system to offer further functionalities Maximum punch is a key feature of this new product, with outstanding lumen output from a light source of less than 20mm making it ideal for high-end fashion stores and jewelry displays. “We believe we have broken new ground with this range extension, further closing the gap between LED spotlighting and traditional CHID lamps,” says Wouter Boxhoorn, Segment Marketing Manager Retail OEM EMEA.

The result of intense collaboration between • No soldering of elegant LED reading lamps was recently LED lighting optical designers and some of • No adhesives awarded the ‘Red Dot Design Award’ and the most experienced mold makers and received an honorable mention. plastics engineers in the business succeeded Carclo / BJB now support the following LUXeXceL’s recent success in making its to reach 2x3,7° FWHM beam angle with the LED’s: ‘Printoptical Technology’ market-ready allows OSTAR SMT while guaranteeing a very • Cree XLamp range ‘on-demand’ manufacturing of products such uniform color mixing and high light output • Osram Dragon as lenses and light distribution structures. The ratio of 90%. Several beams are available: • Seoul P4 advent of this innovative production process 7.5°, 21°, 35°, 7.5°x37° as well as a zoomable • Philips Luxeon Rebel immediately offers the LED lighting industry system to offer further functionalities. completely new growth opportunities. The complete assembly process is as follows: The specification of achieving a highly efficient The connectors (dependent on the LED) and “I am proud our team has succeeded in narrow beam is a technical challenge the STARboard are both fixed with two making this ground breaking technology requiring Gaggione to produce a collimator screws. Electrical contact is by means of two available for the LED lighting market. 45mm in diameter, demonstrating unique push wire terminals. The optic holder is ‘Bottlenecks’ that currently block the experience injecting thick polymer optics. clipped onto the connector, and the optical successful introduction of quality LED lighting system itself clips into this. to the market – in particular in lens This 45 mm series in the LEDNLIGHT development – can now easily be removed” product-line, is the unique answer for lighting The advantage of the BJB system is non- said Richard van de Vrie, CEO of the fixture designers using OSTAR SMT and soldered, providing a transferable quality LUXeXceL Group. looking for powerful multicolor light between LED’s. The complete manufacturing/ concentration. assembly offers a flexible solution for certain RZB CEO Reiner Jürgens is also very pleased applications. with the development: “The production of optics is now more accessible than ever before. The removal of difficult design, Carclo Technical development and manufacturing barriers First Application associated with the production of the optics Plastics in New of LUXeXceL’s offers new possibilities for the lighting industry Partnership with BJB worldwide.” We are both pleasantly surprised New “Printoptical and proud that the first series of lenses has Carclo LED Optics, a division of Carclo been produced for our ‘Mera’ series.” Technical Plastics, is proud to announce that Technology” they are now supplying the BJB holder Ms. Karla Peijs, Queen’s Commissioner for New energy-saving LED fixtures can now be system. This has been specifically developed the province of Zeeland, printed the world’s introduced into the market faster, cheaper to accommodate Carclo’s 20mm optic range. first LED lighting lens today in front of and with greater flexibility. In addition to The system will offer Carclo’s customers a members of the press and distinguished significant time savings, this digital printing greater degree of manufacturing flexibility guests. With this symbolic action, Ms. Peijs technology also opens up new product when choosing how to secure their optic. officially opened the new print platform at the design possibilities for (O)LED lighting LUXeXceL Technology Center in Goes. manufacturers. Graphic design is all that is needed to add logos, technical data or design The first series of LED lenses will be elements into the same production process. introduced in the ‘Mera’ lighting series Moreover, optical adjustments or quick produced by RZB Leuchten in Bamberg, modifications are easy to implement in Germany. The distinctive design of this series production.

LUXeXceL’s printoptical technology can be integrated in thin objects and allows new design ideas, like lens in wood Carclo offers BJB holders for their 20mm optic range

The BJB holder when used in conjunction with Carclo’s optics provides the following advantages – whilst still harnessing the capability of Carclo’s high performance optics:

NEWS PRODUCTS 12

TM Switch Lighting Technical Data of Switch75 calculated energy savings of up to $140.00 Shape: A19 (Edison standard) per bulb over its lifetime. The Switch LED Introduces brightest Fitting: E26 (Standard screw base) bulbs use 85% less energy than incandescent Power: 16 W bulbs and unlike compact fluorescents, they LED Replacement Voltage: 120 VAC do not contain mercury. The purchase price Bulb Line frequency: 50-60 Hertz payback in energy cost savings is realized in Average lifetime: 20,000 hours about one year. Switch Lighting, the only company with the Color temperature: 2750 Kelvin closest alternative to incandescent-quality Light Output: 1150 Lumens “With our unique self-cooling technology, we light, announced a brand new technology that Color Accuracy: 85 CRI make the brightest warm white LED light bulb produces the brightest warm light LED Efficacy: 75 Lumens/Watt available. We offer the most affordable, replacement bulb available. Using their “City Diameter: 2.73 inches energy-efficient light bulb on the market that of Light”TM technology, the bulb creates a Height: 4.41 inches is nearly identical to the regular incandescent self-cooling environment inside, allowing Dimmable: Yes: 20-100% bulbs we’ve come to love.” says Brett maximum brightness with fewer LEDs. With Sharenow, Switch’s Chief Strategy Officer. this technology, Switch Lighting is bringing to “The LED lighting market is being redefined— market the first true 75 watt equivalent warm people want sustainable, energy-efficient light With increased energy costs and white LED replacement bulb at an affordable sources without a compromise in governmental calls for energy saving price. incandescent light quality or design,” says measures, people are increasingly looking for Boris Lipkin, CEO of Switch Lighting. “Switch solutions, but don’t want to give up Features: bulbs can be used just like a regular bulb - aesthetics, including the instant-on and warm • Unique Design: Unique industrial design in all directions, in almost every light fixture light of their regular bulbs. Switch’s “City of within the standard A-19 form factor. and with most any dimmer,” added Mr. Lipkin. Light” offers the same look, feel and quality of • Bright Light Output: 1150 warm white light as an incandescent. lumens—a true 75 W replacement lamp. Switch is designing their LED bulbs to meet • Uncompromising Functionality: Instant on, Cradle to Cradle® principles-continuously beautiful dimming operates perfectly in all and cost-effectively recovering all materials orientations—up, down, and sideways— from the used light bulbs and safely An Efficient Bulb with no overheating or reduction in bulb biodegrading or recycling them. “Components lifetime. won’t necessarily be repurposed into another for Chandeliers and • Lower Total Cost: Lasts up to 20 times light bulb, but could be siphoned into the longer than conventional lighting. broader industrial cycle,” says William Decorative Lighting: • Comfortable Light: More similar to the McDonough, who developed the Cradle to Magnolia LED Lamps warmth and radial flux of an incandescent Cradle protocol with German chemist Michael than any other LED replacement lamp. Braungart. “The unique design of Switch As the world announces its plans to phase • Outstanding Color Accuracy: A brilliant bulbs signals the company’s intention to offer out the 12.5 billion traditional incandescent display of light with a CRI of 85. brilliant lighting as a service for humanity,” bulbs used annually, how would we continue • Highly Sustainable: Reduced energy added McDonough. to light our artistic decorative lighting, consumption, performing brilliantly for especially crystal chandeliers? We would thousands of hours, free of hazardous Because of the unique cooling system, Switch need a good energy efficient light source that materials. All lamp components are light bulbs can be used in any orientation with can still deliver the brightness and shine. completely reusable or recyclable, so no no compromise to their 20,000 hour life (10-15 part ever goes into a landfill. years). Based on a 75 watt-equivalent bulb used in a home for 5 hours a day, Switch has

Switch Lighting’s self- cooling technology offers the best and brightest warm incandescent-quality light

Some examples out of SFT’s Magnolia LED lamps range which can replace chandelier bulbs perfectly

SFT Holland Cooperative U.A will introduce its brand new Magnolia LED Lamps in the 3rd LED / OLED lighting Expo in Big Sight, Tokyo.

Product Benefits: • No mercury, no UV light, no hazardous material, benefit for your health and environment friendly • 85% energy saving, 5 W LED bulb substitutes 40 W incandescent bulb • Long life, 25,000 hrs guarantees no maintenance for 10 years • Similar size and shape as traditional bulbs, not necessary to change light fixtures • Standard cap base fulfilling the requirements of your country • Excellent stability of light color temperature by CREE® white LED technology • Truer vision by high color rendering index • Spark warm light by clear bulb, comfortable soft warm light by frosted bulb

Applications: • Chandeliers, ceiling lights, wall scones, desk lamps, floor lamps, and decorative luminaries • Hotel, restaurant, conference, meeting room, show room • Retail lighting, museum lighting, hospitality lighting, accent lighting, architectural lighting

The Magnolia LED Lamp with a 300 degree beam angle, 300 lumen brightness at 2700 K, is the first energy efficient lamp to truly duplicate the look and feel of the incandescent bulb without the heat and high power usage. It uses only 5W to replace a traditional 40 W incandescent. These features make it the perfect energy efficient bulb for chandeliers and decorative lighting. Currently, there is no other LED lamp that is able to do this.

Gordon Tan, SFT's Chief Global Marketing Officer said “Now the world does not need to worry about how to light their beautiful chandeliers when they can no longer buy incandescent bulbs.”

Magnolia LED Lamp is patented worldwide and now being launched in more than 20 countries globally.

Low cost 3W and 6W LED-Driver with Constant Current Supply in Ultra Compact Design RECOM announces the release of an extension to their range of isolated AC/DC-LED-Drivers with constant current-output in 3 to 6 Watt power supply

Advances in LED technology require low power of 1 W or 3 W for LED-illumination. The two new families meet the growing demand for low cost drivers below the previously available products with 12 W, 20 W, 30 W and 60 W power. With an input voltage range of 90 to 264 VAC the new drivers can be used universally on all networks worldwide. NEWS PRODUCTS 14

RECOM’s RACD Applications: series LED drivers are intended to drive • The device can be used in all LED lighting three, respectively six applications that require: 1 W LEDs in ultra- very efficient, low THD compact design high PF true universal input voltage cost-effective power supply solution between 10 W and 300 W

Features and Benefits: • Integrated PFC and flyback controller • True universal mains supply operation: 70 V (AC) to 305 V (AC) • High level of integration, resulting in a: very low external component count cost-effective design • On-chip start-up current source • Valley/zero voltage switching for minimum switching losses • Frequency limitation to reduce switching losses • PFC is switched off when a low load is detected at the flyback output The RACD03 can drive three 1W LEDs with • Valley switching for minimum switching 350 mA or single 3 W LED with 700mA NXP’s New Efficient losses constant current. The LED-Driver has flying SSL Solutions for • Frequency reduction with fixed minimum leads. RACD03 is IP65 rated and can be used peak current at low power operation in damp areas such as sanitary facilities, Industrial, Warehouse • Safe restart mode for system fault exterior lights or cellar. conditions and Street Light • Continuous mode protection by means of The RACD06 can drive six 1 W LEDs with NXP Semiconductors N.V. announced an demagnetization detection 350 mA constant current or alternative two addition to its broad GreenChip™ SSL family • Under Voltage Protection (UVP) (fold back 3 W LEDs with 700 mA constant current. The of products, the GreenChip SSL4101T during overload) LED-Driver has screw terminals and is ideal controller IC, which offers new levels of • Accurate Over Voltage Protection (OVP) for for applications that include low cost cabinet professional-grade performance for Solid both converters lighting, reading lamps and bathroom State LED lighting power supplies. The • Open control loop protection for both spotlights. Both drivers are designed for panel GreenChip SSL4101T enables LED lighting for converters mounting and are supplied with mounting medium to high power commercial and • IC over temperature protection screws. professional applications with industry-leading • Low and adjustable Over Current Protection performance in Total Harmonic Distortion (OCP) Although the converters are very compact (THD) of less than 20 percent, a high Power • General purpose input for latched with a low profile case that is 39 mm x 30 mm Factor (PF) of .99, and high efficiency of 94 protection x 21 mm high for the RACD03 and 58 mm x percent. 35 mm x 21 mm for the RACD06, they contain a fully featured input filter and meet Typical application EN61347, EN55015 and FCC18A without the circuit with NXP’s need for any external components. The GreenChip SSL4101T converters offer 3 kVAC isolation and are CE and EN safety certified. UL8750 certification is pending. The LED drivers are designed to give a long, trouble-free life. The “Design Lifetime” is rated at >20,000 hours, equivalent to 8 hours daily operating time up to 7 years. The warranty period is 3 years.

LED test & measurement solutions from the world leader

Instrument Systems continues to set the benchmark in LED metrology. Whether testing individual LEDs (standard or high-power), LED modules, or OLEDs - the global LED industry relies on us to engineer superior measurement equipment for high-speed production testing and high-performance R&D and QC applications.

Our instruments provide accurate and reliable results as per CIE recommendations and methods:  Luminous flux [lm], luminous intensity [cd], and luminance [cd/m2]  Chromaticity coordinates x,y,z and u’v’  Color temperature and color rendering index  Dominant wavelength and spectral data  Spatial radiation pattern

light measurement

Instrument Systems Germany · Phone: +49 89 45 49 43 0 · [email protected] · www.instrumentsystems.com NEWS PRODUCTS 16

“Today’s LED luminaire manufacturers are Macroblock IR’s IRS2548D LED demanding increased power supply efficiency at lower costs in order to address new LED Introduces MBI6902 Control IC Increases application segments,” said Jacques Le Berre, director of marketing and business for T8 and E27 Efficiency, Simplifies development, lighting solutions, NXP Applications Design and Reduces Semiconductors. “GreenChip technology lies at the heart of NXP’s cost-effective, highly- Macroblock introduces a new non-isolated, Overall System Cost efficient power and lighting ICs. The newly step-down and high efficiency AC / DC LED International Rectifier, IR®, a world leader in announced GreenChip SSL4101T offers a driver, MBI6902, especially for T8 and E27 power management technology, introduced professional-grade solution with levels of lighting applications. The MBI6902 achieves the IRS2548D Switched Mode Power Supply efficiency of up to 94 percent, which is superior efficiency in high brightness LED (SMPS) control IC for energy efficient enabling LED adoption into a wider-range of lighting applications. For example, the applications for high power Light Emitting professional lighting applications such as high efficiency is over 90% when lighting up Diode (LED) illumination including LED street bay and low bay lighting found in warehouses; 6-LEDs @ VAC =110 V, 350 mA. The MBI6902 lighting, stadium lighting and theatrical and street lighting, where brightness and is able to drive external MOSFET current up to lighting. dependable illumination are essential.” 3 A. In addition, the MBI6902 requires only a few external components. The high efficiency The IRS2548D, which combines Power Factor The GreenChip SSL4101T is based on NXP’s and compact solution of MBI6902 make it Correction (PFC) and half-bridge driver in a unique high voltage process and enables most applicable for T8, E27 and general single IC offers greater than 88% efficiency for direct start-up from the rectified universal illumination applications. a 40 V / 1.3 A HBLED load to deliver a higher mains voltage in an effective, eco-friendly way. efficiency solution compared to alternative The multi-chip module contains both a flyback The MBI6902 accepts wide universal AC flyback converter solutions at power levels controller and a controller for Power Factor input from 80 VAC to 265 VAC and regulates above 60 W. Correction, and provides high efficiency at all the accuracy of preset output current within power levels. The new GreenChip SSL4101T is ±5% by switching the external MOSFET. Features: ideally suited for LED lighting applications that Besides, the MBI6902 has multiple features to • PFC, system control and half-bridge driver require a very efficient, low THD, high PF, true protect the controller from fault conditions, in one IC universal input voltage and cost-effective including under voltage lockout (UVLO), over • Critical-conduction mode boost-type PFC power supply solution ranging between voltage protection (OVP), over current • Programmable PFC over-current protection 10 W and 300 W. protection (OCP), and LED open-circuit and • Half Bridge Driver short-circuit protection. Additionally, to ensure • Half Bridge Over Current Protection the system reliability, the MBI6902 is built with • Variable Frequency Oscillator the thermal protection (TP) function. The • Fixed internal 1.6 us HO and LO dead time MBI6902 is now available in MSOP-8L • Internal bootstrap MOSFET package. Samples and reference designs are • Internal 15.6 V zener clamp diode on Vcc now available. • Micropower startup (250 μA) • Latch immunity and ESD protection

IR's new IRS2548D schematics for a typical application

Bias ruggedized LED driver modules meet Typical Applications: NEMA 6P / IP67 moisture and submersion Diodes LED Driver for • Isolated LED Drivers and easily satisfy the strict requirements for • Power Supplies MR16, 12V and 24V outdoor architectural building and low-bay garage LED lighting. The LED drivers are “By incorporating both control stages into a LED Lamp Design rated for 3,000 VAC isolation and feature single IC, the new IRS2548D provides an The AL8806 buck LED driver from Diodes inherent over-current, short circuit (shorted integrated solution for LED power supplies Incorporated is capable of producing a string), overload and open circuit (string break) that simplifies design and helps reduce overall constant current of up to 1.5 A from voltage protection. All modules are specified for full- system cost, while providing significant sources of between 6 V and 30 V. Suiting rated power over the temperature range of energy savings,” said, Peter Green, LED MR16, 12 V and 24 V LED lamp design, the -40 to +85°C and operate at a nominal 80% Group Manager, IR’s Energy Saving Products driver ensures a 5% average LED current efficiency, resulting in some of the highest Business Unit. accuracy for up to 9 high power LEDs over lumens/watt end-to-end efficacy ratings for the wide operating voltage range, helping to LED solutions in the market. The new device achieves PWM dimming significantly improve inter-lamp luminance down to less than 2% light output and offers With a footprint of only 1.3 x 1.9 inches and matching. protection features that include less than 1 inch in height, the BPWXL6 programmable PFC and half-bridge over- provides up to 6 Watts of output power for LED Applications: current protection, latch immunity, and ESD string voltages up to 21 VDC. In the same • High power MR16 lamps protection. The IRS2548D also includes package, the BPWXL4 provides up to 4 Watts • General illumination lamps variable frequency oscillator, fixed internal of output power for LED string voltages up to • Multi-die LED driver 1.6 us deadtime, internal bootstrap MOSFET, 12 VDC. The BPXL10 is a 10 Watt driver internal 15.6 V zener clamp diode on Vcc, and module for LED strings rated up to 30VDC, and Features: micropower startup (250 µA). has a package size of 2.1 x 2.3 inches with a • LED driving current up to 1.5 A height of 1.25 inch. Standard connections are • Better than 5% accuracy 11 inch, 18AWG ‘flying leads’ and dual • High efficiency up to 98% mounting slots for ease of installation. • Operating input voltage from 6 V to 30 V BIAS Low-Power • High switching frequency up to 1MHz Bias Power LED Driver modules comply with • PWM/DC input for dimming control Ruggedized AC-DC UL/CSA and EN Product Safety • Built-in output open-circuit protection Requirements (UL8750 Class 2) and meet • SOT25 MSOP8-EP: Available in “Green” LED Drivers Meet conducted EMI emissions EN 55022, Class B molding Harsh Requirements and FCC Part 15, Class B. The modules have • Compound (No Br, Sb) with lead free finish/ for Outdoor Lighting an MTBF rating of >500K operating hours. RoHS compliant Bias Power’s new BPWXL Series of 4, 6 and Typical application 10 Watt constant current LED drivers offer circuit using Diodes’ 350mA constant current operation with 1% AL8806 buck LED regulation over the entire input voltage range driver of 100-308 VAC, 50/60 Hz. Additionally, the drivers have unique cold-starting circuitry tested to -55°C, that is proven to kick-start LEDs even in frigid outdoor lighting fixture designs. The LED drivers are based on Bias’ patented* circuit designs incorporating a custom ASIC controller.

Bias Power’s new The high current handling of the AL8806 BPWXL Series 10 Watt constant current LED means it will also meet the needs of the latest driver multi die package LEDs, where current levels above 1 A are required. This simple, cost- effective driver is packaged in the small footprint low thermal impedance MSOP-8EP, supporting higher LED current drive at higher ambient operating temperatures. Device efficiency is high at up to 98%.

Maximum output current is simply set via a resistor and switching at a frequency of up to 1 MHz, the driver helps reduce the size of supporting external components, enabling

PCB size to be minimized. Lamp dimming is LDD series are designed to be mounted on applications include street lighting, landscape achieved by applying either a DC voltage or the system PCB of lighting fixture. Their lighting, tunnel lighting, household lighting, PWM signal that provides a wide range of typical deployment is to connect to the output and all kinds of indoor/outdoor LED lighting. brightness control that doesn’t over drive the of CV (constant voltage) mode AC-DC LED LED current. power supply for providing a constant current to drive LEDs. Take a typical LED lighting fixture with multiple LED strings internally as Thermal Technology an example, using LDD series not only can Provides Newly Mean Well maintain good current balance for each LED string and hence ensure the long life of LEDs, Developed K1 Announces New but also can save the effort of sorting the Vf value of LEDs. Besides, because of the Sapphire Growers Series of DC/DC independent constant current nature, failure in Thermal Technology, a leading manufacturer Constant Current any LED string driven by the LDD series won’t of crystal growth equipment and high affect the others, and each string can be temperature furnace systems, recently LED Drivers connected for a different number of LEDs finalized a sales agreement with Chongqing MEAN WELL announced two kinds of according to system design requirements. Silian Optoelectronics Science & Technology encapsulated module type DC-DC buck Co., Ltd. (Silian) for multiple Model K1 converters for LED driving purposes - LDD-L With non-isolated Buck topology design, the sapphire crystal growers. and LDD-H series. With constant current LDD series possess up to 97% of extremely mode output, LDD-L features with 9-36 VDC high efficiency and can operate between -40 “This new sales order signals continued input and 2-32 VDC output while LDD-H to +85°C of ambient temperatures by only industry acceptance of Thermal Technology’s possesses a wide range of 9-56 VDC input free air convection (up to 71°C for 600 mA ~ 1 high-productivity industrial tool for sapphire and 2-52 VDC output. Both series provide A models). Built-in EMI filter, these LED drivers crystal growth and will benefit both Silian and multiple output current options of 300 mA / comply with EMI requirements per EN55015 Thermal Technology going forward,” says 350 mA / 500 mA / 600 mA / 700 mA / 1 A lighting regulation without connecting any Matt Mede, Thermal Technology president (LDD-H only) for LED system designers to external EMI restraint components and are and CEO. Shipments of Silian’s multiple-unit choose from. very convenient for PCB installations. The order began in April, 2011. compact size also offers system designers great flexibility in PCB layout for power stage Thermal Technology’s newly designed Model design. Other standard functions include K1 crystal grower is intended for LED PWM dimming, protections of short circuit substrate production. The tool’s short cycle and over temperature, wide range of input/ time makes it the most productive grower output voltage. Besides, fully encapsulated commercially available. To satisfy the high packaging can help them withstand the demand of the rapidly growing sapphire influence of dust and moisture comes from all market, Thermal Technology is shipping kinds of harsh environments. Suitable systems weekly.

Mean Well's new LDD-L and LDD-H constant current DC/DC buck converters

Main Features: • Constant current (C.C.) mode output • Wide input / Output range • 97% high efficiency • Built-in PWM dimming function • Cooling by free air convection • Protections : Short circuit /Over temperature • UL94-V0 level plastic case • Approval : FCC / CE • Dimension(LxWxH) : LDD-L - 22.6 x 9.9 x 8.4 mm LDD-H - 31.8 x 20.3 x 10.2 mm • 2 years warranty

Sapphire substrate (left) for LEDs, grown with Thermal Technology’s K1 crystal grower

NEWS PRODUCTS 20

Essemtec Builds Same soldering conditions over the entire designed with a diameter of 1.9 meters to PCB length: facilitate precise measurement of total radiant Production Line for The light efficiency and life expectation of LED power and luminous flux at lamps, luminaires tubular lamps strongly depend on the equality and large LED modules. LED Tubular Lamp of the LED soldering quality because the Until recently LED TL-tubes, a replacement for solder joint is an important element of the fluorescent lamps, had to be manufactured in temperature management system. Therefore, a lavish modular design. In the future, using each LED must be soldered precisely and the new LED assembly line with a large-area with identical temperature profiles. Achieving printer from Essemtec, PCBs for such lamps such stability over the PCB length of 180 cm can be manufactured fully automatically in a is not a simple task.Essemtec builds an single, cost-efficient production run. advanced RO-VARIO reflow oven with special heating zones for such demanding soldering Printing and assembling 180x50 cm PCBs: tasks. The oven features a homogeneous A complete turnkey production line for LED temperature profile across the transport tubular lamps consists of a large-area printer, direction and longitudinal direction, and the three Cobra pick-and-place machines, a furnace precisely controls the soldering large-area reflow oven and modules for PCB temperature. In this way the reflow oven The ISP 2000 is the largest member of the handling. The line prints, assembles and ensures that all LEDs on a 180 x 50 cm PCB well-established family of premium integrating solders PCBs with sizes up to 180x50 cm in are soldered the same way. spheres produced by Instrument Systems one run. Its throughput is in the range of 54,000 LEDs per hour. Complete turnkey from one source: The ISP2000 incorporates all the unique Essemtec, the Swiss manufacturer of capabilities that brought success to its smaller The new large-format printer, currently in production systems for electronics, delivers peers of the well-established family of concept phase, is designed for printing large, the complete production line including printer, premium integrating spheres. These heavy boards. The innovative transport pick-and-place, reflow oven and handling characteristics are particularly effective for system provides excellent planarity during modules. The line can be completed with testing solid-state lighting (SSL) products, printing, even when processing pre-scored automatic dispensing systems and storage conventional lamps and luminaires. The ISP multi-boards and circuits made from units. Essemtec also delivers software for 2000 is equipped with an auxiliary lamp to composite materials. Printing direction is production planning and optimization. compensate for self-absorption, a temperature longitudinal over a width of 50 cm. Across sensor to monitor the thermal conditions of the the entire length of 180 cm, the printing interior, and a detector port incorporating a results are consistent and of high quality. fiber adapter to link the sphere with all Instrument Systems spectroradiometers from Instrument Systems. In LED lamps, production speed is important The company offers a complete package of as well as the precise alignment and Launches Large calibration accessories for the ISP 2000. placement of the LED components. Cobra type SMD pick-and-place machines are ideal Integrating Sphere The ISP 2000 can be used to carry out for this task as they are fast, flexible and for Testing SSL Light measurements at 4π and 2π geometry. The highly accurate. A Cobra pick-and-place can maximum sample size is 600 mm x 300 mm x place LEDs of any size and shape and also Sources 300 mm in the center and the maximum can place other SMD components. Vacuum The ISP 2000 from Instrument Systems is the sample diameter is 600 mm at the external tool tips are specially coated to prevent any latest pioneering development launched by measurement port. A lamp holder is available damage on the LED surface or lens. Three the leading manufacturer of light for mounting the test specimen inside the pick-and-place machines are producing measurement systems worldwide. This sphere. It accommodates optional adapters simultaneously. integrating sphere has been specifically for all standard lamp sockets. A sample stage can be used instead of the lamp post for mounting non-standard sample sizes, for example complete luminaires and LED modules. This stage provides a footprint of 200 mm x 150 mm and a 16-pole terminal strip for connecting to a power supply or control circuit. A robust, rail-mounted sliding mechanism delivers light-tight closure for the ISP 2000 and permits the sphere to be opened easily for quick access.

The complete turnkey to manufacture LED TL-tubes to replace FL-tubes from one source

New Method for Results of the study, titled “Defect-reduced green. This means developing a high- green GaInN/GaN light-emitting diode on performance green LED could therefore likely Manufacturing the nanopatterned sapphire,” were published in lead to a new generation of high- the journal Applied Physics Letters, and are performance, energy-efficient display devices. Elusive Green LED featured in the Virtual Journal of Nanoscale with Higher Efficacy Science & Technology, published by the The problem, however, is that green LEDs are American Institute of Physics and the much more difficult to create than anyone Researchers at Rensselaer Polytechnic American Physical Society. The paper may be anticipated. Wetzel and his research team are Institute have developed a new method for viewed online at: http://dx.doi. investigating how to “close the green gap,” manufacturing green-colored LEDs with org/10.1063/1.3579255 and develop green LEDs that are as powerful greatly enhanced light output. as their red or blue counterparts. The research program is supported by the U.S. Department of Energy National Energy Technology Laboratory (NETL) Solid-State Lighting Contract of Directed Research, and Theorists from UC the National Science Foundation (NSF) Smart Lighting Engineering Research Center (ERC), Santa Barbara Claim which is led by Rensselaer. that LED Efficiency

LED lighting only requires a fraction of the Puzzle Is Solved energy required by conventional light bulbs, Researchers at the University of California, Rensselaer researchers discover a new method and LEDs contain none of the toxic heavy Santa Barbara, say they have figured out the for boosting the light output of green LEDs metals used in the newer compact fluorescent cause of a problem that has made light- light bulbs. In general, LEDs are very durable emitting diodes (LEDs) impractical for general The research team, led by Christian Wetzel, and long-lived. lighting purposes. Their work will help professor of physics and the Wellfleet engineers develop a new generation of Constellation Professor of Future Chips at The holy grail of solid-state lighting, however, high-performance, energy-efficient lighting Rensselaer, etched a nanoscale pattern at the is a true white LED, Wetzel said. The white that could replace incandescent and interface between the LED’s sapphire base LEDs commonly used in novelty lighting fluorescent bulbs. and the layer of gallium nitride (GaN) that applications, such as key chains, auto gives the LED its green color. Overall, the new headlights, and grocery freezers, are actually “Identifying the root cause of the problem is technique results in green LEDs with blue LEDs coated with yellow phosphorus an indispensable first step toward devising significant enhancements in light extraction, – which adds a step to the manufacturing solutions,” says Chris Van de Walle, a internal efficiency, and light output. process and also results in a faux-white professor in the Materials Department at UC illumination with a noticeable bluish tint. Santa Barbara who heads the research group The discovery brings Wetzel one step closer that carried out the work. to his goal of developing a high-performance, The key to true white LEDs, Wetzel said, is all low-cost green LED. about green. High-performance red LEDs and Van de Walle and his colleagues are working blue LEDs exist. Pairing them with a to improve the performance of nitride-based “Green LEDs are proving much more comparable green LED should allow devices LEDs, which are efficient, non-toxic and challenging to create than academia and to produce every color visible to the human long-lasting light sources. They investigated a industry ever imagined,” Wetzel said. “Every eye – including true white, Wetzel said. phenomenon referred to as “droop”—the drop computer monitor and television produces its Today’s computer monitor and television in efficiency that occurs in these LEDs when picture by using red, blue, and green. We produces its picture by using red, blue, and they’re operating at the high powers required already have powerful, inexpensive red and Unlike scientists blue LEDs. Once we develop a similar green from the University LED, it should lead to a new generation of of California, Santa high-performance, energy-efficient display Barbara, some other and illumination devices. This new research scientists are not finding is an important step in the right convinced that Auger recombination is the direction.” cause for droop - other models are also Sapphire is among the least expensive and proposed widely used substrate materials for manufacturing LEDs, so Wetzel’s discovery could hold important implications for the rapidly growing, fast-changing LED industry. He said this new method should also be able to increase the light output of red and blue LEDs.

to illuminate a room. The cause of this decline BRIDGELUX and not widely available. As a result, has been the subject of considerable debate, production costs have inhibited the but the UC Santa Barbara researchers say Demonstrates widespread adoption of LED lighting in homes they’ve figured out the mechanism and commercial buildings. But growing GaN responsible for the effect by performing Dramatic on larger, low-cost silicon wafers that are quantum-mechanical calculations. Advancements in compatible with modern semiconductor manufacturing can deliver a 75% LED droop, they conclude, can be attributed GaN-on-Silicon improvement in cost over current approaches. to Auger recombination, a process that occurs in semiconductors, in which three Technology for SSL The 135 Lumen per Watt performance was charge-carriers interact without giving off Bridgelux Inc., a leading developer and achieved at a CCT of 4730 K using a single light. The researchers also discovered that manufacturer of LED lighting technologies and 1.5mm power LED operated at 350 mA. indirect Auger effects, which involve a solutions, announced that it has achieved a These LEDs have extremely low operating scattering mechanism, are significant—a major breakthrough with the demonstration of voltages, requiring just 2.90 V at 350 mA and finding that accounts for the discrepancy 135 Lumens per Watt GaN-on-Silicon based <3.25 V at 1 A. The low forward voltage and between the observed degree of droop and LED technology. This represents the excellent thermal resistance of the devices that predicted by other theoretical studies, industry’s first commercial grade performance make them ideally suited for high- which only accounted for direct Auger for a Silicon-based LED. performance, illumination-grade applications. processes. Optimization of the epitaxy process on 8-inch Si wafers will make LED manufacturing In nitride LEDs, “These indirect processes compatible with existing automated form the dominant contribution to the Auger semiconductor lines. recombination rate,” says Emmanouil Kioupakis, a postdoctoral researcher at UC The move to a Silicon substrate will be a Santa Barbara and lead author of a paper revolutionary step for the LED industry, and published online April 19 in Applied Physics Bridgelux is well- positioned to take full Letters. The other authors are Van de Walle, advantage of the introduction of this Patrick Rinke, now with the Fritz Haber technology. Over the past 5 years, Dr. Steve Institute in Germany, and Kris Delaney, a Lester, one of the industry’s pioneers in LED project scientist at UC Santa Barbara. Research and Development, has fostered a world-class team of Bridgelux materials LED droop can’t be eliminated because Auger scientists and chip design engineers effects are intrinsic, but it could be minimized, dedicated to GaN-on-Silicon R&D. the researchers say, by using thicker quantum Concurrently, industry-wide research and wells in LEDs or growing devices along development of GaN growth on Silicon has non-polar or semi-polar growth directions in increased rapidly. And as a result, the GaN on order to keep carrier density low. Growing LEDs on low-cost large diameter Silicon performance levels reported by silicon substrates needs special knowledge Bridgelux are comparable to state-of-the-art “With Auger recombination now established sapphire-based LEDs available 12-24 months as the culprit, we can focus on creative When grown at scale, most LED epitaxial ago. The company anticipates the delivery of approaches to suppress or circumvent this wafers use sapphire or silicon carbide its first commercially available GaN-on-Silicon loss mechanism,” Van de Walle says. substrates as the starting material. But large products over the course of the next two to diameter sapphire and silicon carbide three years. The work was supported by the Center for substrates are costly, difficult to process, Energy Efficient Materials, funded by the U.S. An optimized epitaxy Department of Energy, and by UC Santa process on 8-inch Barbara’s Solid State Lighting and Energy Si wafers will make Center. Computational resources were LED manufacturing provided by the U.S. DoE’s National Energy compatible with Research Scientific Computing Center at existing automated semiconductor lines Lawrence Berkeley National Laboratory, the California NanoSystems Institute’s Computing Facility at UC Santa Barbara, and the National Science Foundation-funded TeraGrid.

Reference: “Indirect Auger recombination as a cause of efficiency droop in nitride light-emitting diodes” - DOI: 10.1063/1.3570656

OSRAM Laboratory: Bright warm white light with high efficiency is combined know-how in all aspects of the particularly important for lighting applications production process. These include epitaxial Efficiency Record for in the residential sector. The laboratory setup growth, thin-film chip architectures, for a warm white LED shows the enormous conversion processes and package Warm White potential of these energy-saving technologies. OSRAM Opto Semiconductors has set a new semiconductor light sources: The peak value laboratory record of 142 lm/W for the of 142 lm/W measured under standard efficiency of a warm white LED light source. conditions is achieved at a color perception With a correlated color temperature (CCT) of that very closely matches that of a classic Advanced Materials 2755 K the LED achieves a good color incandescent lamp (color coordinates cx rendering index (CRI) of 81. Measurements 0.46/ cy 0.41 on the Planckian curve). Researchers were taken under standard conditions: room "Brighten" Future of temperature and pulsed mode at an operating “If we explore this technical approach further current density of 350 mA/mm². and allow deviations from the Planckian curve OLED Technology we should even now be able to achieve higher Chlorine: an abundant and readily available efficiency values of up to 160 lm/W for a halogen gas commonly associated with the correlated color temperature of 3000 K sanitation of swimming pools and drinking (cx 0.45 / cy 0.44)”, said Dr. Norwin von Malm, water – could a one-atom thick sheet of this Predevelopment Manager at OSRAM Opto element revolutionize the next generation of Semiconductors. “If we apply this approach flat-panel displays and lighting technology? to a 2 mm² chip we can improve efficiency by a further 10 to 15 percent for the same In the case of Organic Light-Emitting Diode operating current. We would then expect (OLED) devices, it most certainly can. Primary 180 lm/W for a pure warm white LED and researchers Michael G. Helander (PhD good color rendering.” Candidate & Vanier Canada Graduate The laboratory setup for a warm white LED Scholar), Zhibin Wang (PhD Candidate), and achieves a peak value of 142 lm/W directly on The increase in efficiency was made possible led by Professor Zheng-Hong Lu, in the the Planckian curve at 2700 K; an optimized by combining new procedures in thin-film and Department of Materials Science & setup at 3000 K could achieve 160 lm/W UX:3 chip technologies and in conversion. Engineering at the University of Toronto, have Development engineers at OSRAM Opto found a simple method of using chlorine to Semiconductors have benefited here from drastically reduce traditional OLED device

complexity and dramatically improve its It turns out that it’s remarkably easy to Correction: Author's efficiency all at the same time. By engineering engineer this one-atom thick layer of chlorine a one-atom thick sheet of chlorine onto the onto the surface of ITO,” says Helander. “We Reference in Index surface of an existing industry-standard developed a UV light assisted process to electrode material (indium tin oxide, ITO) achieve chlorination, which negates the need of LpR24 found in today’s flat-panel displays, these for chlorine gas, making the entire procedure LED professional apologizes for accidentally researchers have created a medium that safe and reliable.” having used a wrong author's reference for allows for efficient electrical transport while the article "Advanced Lighting Technology eliminating the need for several costly layers The team tested their green-emitting “Cl- Needs an Advanced Color Rendition Metric" found in traditional OLED devices. OLED” against a conventional OLED and in the Index of LED professional Review 24 - found that the efficiency was more than March/April issue. doubled at very high brightness. “OLEDs are known for their high-efficiency,” describes Please take note of the corrected Helander. “However, the challenge in reference: conventional OLEDs is that as you increase Advanced Lighting Technology Needs an the brightness, the efficiency drops off Advanced Color Rendition Metric rapidly.” Using their chlorinated ITO, this team by Artūras Žukauskas and Rimantas of advanced materials researchers found that Vaicekauskas, Vilnius University; they were able to prevent this drop off and Michael Shur, Rensselaer Polytechnic achieve a record efficiency of 50% at 10,000 Institute cd/m2 (a standard florescent light has a The research team that developed the “Cl-OLED” (left to right): Zhibin Wang (PhD brightness of approximately 8,000 cd/m2), Candidate), Professor Zheng-Hong Lu, and which is at least two times more efficient than Michael Helander (PhD Candidate + Vanier the conventional OLED. Canada Graduate Scholar) hold their Cl-ITO enabled OLED devices “Our Cl-ITO eliminates the need for several stacked layers found in traditional OLEDs, reducing the number of manufacturing steps and equipment, which ultimately cuts down on the costs associated with setting up a production line,” says Professor Zheng-Hong Lu. “This effectively lowers barriers for mass production and thereby accelerates the adoption of OLED devices into mainstream flat-panel displays and other lighting technologies.”

Red, green and blue Cl-ITO-OLEDS from the The results of this work titled "Chlorinated University of Toronto Material Science and Engineering Institute Indium Tin Oxide Electrodes with High Work Function for Organic Device Compatibility" were published online in the journal, Science, on April 14, 2011 (Science DOI: 10.1126/ science.1202992).

New Designed LED Tubes with TÜV Certification from Willighting In order to satisfy the safety requirements of LED tube installation from EU, Willighting adopts new TUV standards and schemes for producing. New designed LED tubes are safer and easier to replace the traditional tubes. Keep your ballast, then simply remove the starter and replace with new one from Willighting. There is no change for the existing circuit.

For more detailed technical and sales information, please contact Willighting sales team.

NEW! Does your driver match the life span of your LEDs? RECOM's new 3, 6, 12, 20 and 60W AC Input LED Drivers do!

✔ Constant current outputs of 0.35/0.5/0.7/1.05 & up to 4.2A ✔ Universal AC input voltage (90 to 264VAC) ✔ Power factor corrected (RACD12/20/60) ✔ 3kVAC isolation ✔ Fused input and protected output ✔ Input and output screw terminals ✔ Additional 5.5mm socket output connection ✔ Meets UL8750, UL1310, EN61347 & EN55015 ✔ Design lifetime up to 70.000 hrs (RACD12/20/60) ✔ 5-year warranty (RACD12/20/60)

Introducing the new RACD series - low power AC input LED drivers. RECOM is now offering a low cost solution for low power Solid State Lighting. The family includes 3W, 6W, 12W, 20W and 60W modules in varying packages capable of driving up to 19 high brightness LEDs or high power arrays. Building an LED lamp has never been easier! RECOM LED Drivers are compatible with most LEDs in the industry. We work closely with the leading LED manufacturers to bring to the market the right drivers for the right LEDs.

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LED Investor Forum 2011 - Santa Clara

Alan R. Miles reports exclusively for LED professional about the expectations of venture capitalists, what manufacturers are planning for the near future, market trends and sales forecasts which were presented at the one-day Investor Forum in Santa Clara.

At the recent Strategies in In 2010, LED performance was no replacements, some fluorescent Light meeting in Santa Clara, longer a limiting factor for solid-state replacements and niche markets. In California, Pennwell Publishing lighting, since the best commercial the near future, the rapid adoption of hosted a one-day Investor cool whites had achieved 160 lm/W (a LEDs for street lighting will produce Forum that indicated a global 10x improvement over the LED another significant LED market growth interest in the financial support performance in 2000) and warm segment. Cannacord Genuity, an for light emitting diode (LED) whites, with 109 lm/W efficiencies, investment company, is also a lighting companies. Several were over 3x better. At these high proponent for LEDs and their in-depth hundred attendees were present lumen levels, the disruptive LED can research indicates that the adoption of at this event, including many also be considered as a serious LED lighting will achieve about a 46% venture capital representatives contender for fluorescent lamp market penetration by 2020, a value seeking suitable investments replacement, especially with a recent chosen in the centre of the estimated plus some companies with LED tube replacement offering for T-5 low to high range of 30-60%. This promising LED lighting products fluorescent lamps, namely the D-LUX® selected level of market penetration that were seeking additional from THE DIGITAL LIGHTTM could remove a cumulative 8.4 billion

investment for expansion Company. This market opportunity can tonnes of CO2 from the air, an amount purposes. Vrinda Bhandarkar, only improve as LED efficiencies equal to the emissions from all the cars from Strategies Unlimited, improve and as the dollar per in the world! opened the proceedings with kilolumen cost of LEDs continues to an overview of the LED lighting fall. In the same 10 year period, the Entertainment lighting is another markets where LED luminaire average lumen output from a one watt example of LED efficiency and although development is rapidly changing cool white LED package has increased it is not a large market segment, it has the industry structure. She noted more than 20 fold and the $/kilolumen been an industry leader and a rapid that LED lighting companies cost has decreased by more than 10 x. innovator of LED technology, because raised about $145 million of Today, the significant LED lighting coloured LEDs use less power than new capital in the USA in 2010 market segments include commercial other sources and require no filter gels, and halfway through February and industrial, architectural, retail no moving parts, yet they can provide 2011 an additional $22 million in display, flashlights, safety, outdoor easily controllable high flux lighting with investments had been placed. area, and solar off-grid. However, rapid switching attributes. As an The maturation of the LED use in despite continuing reductions in LED example, at the recent 2011 US lighting is creating a convergence costs and improving efficiencies, the Superbowl, all the lighting (except the of light sources, ballasts and cost of the LED can still be a limiting spot lighting on the lead entertainers) fixtures in a market where LED factor for some general lighting was LED based and allowed low power luminaires and replacement applications. Vrinda reported the LED rapidly switched illumination for the lamps are developing into new luminaire lighting market to be almost whole cast of performers. market segments. Fortunately $5 billion in 2010. Both the for LED lighting, the investment replacement lamp and consumer In the next 5-year period, Vrinda community is actively looking to portable markets were 20% of this forecast the total LED markets to support new ventures in these value with the architectural and increase by 4x to $20 billion, the LED rapidly growing LED market commercial segments, each being luminaire market to more than double segments. about 15%. Much of this growth in LED and the replacement LED lamp market use has been cost of ownership based to grow by a factor of 11 or more to and supported by incandescent exceed $11 billion by 2015. Much of this

Issue 25 2011 © 2011 LUGER RESEARCH e.U. LED market growth will be brightness LED green emission supported by products that offset that does not vary with the rising energy costs, reduce applied current. Ben reported greenhouse emissions, benefit that standard GaN LEDs are from the compatibility of use of often limited to the emission of LEDs with intelligent lighting 60-100 lumens/mm2, whereas controls, meet national security GaN devices grown on semi- and needs, support incentives such as non-polar substrates have the incandescent phase outs and potential for up to 3000 lm/mm2 mercury reduction and for some light outputs that will allow the countries, relieve national manufacture of either more pressures to conserve foreign intense LED sources or smaller exchange resources for fuel used LED chips for the same light for lighting. This growth can now output, thus lowering LED be supported by a rapid materials costs. Assuming that proliferation of base-compatible, the next investment round for 90 lumen per watt or better, LED Inlustra is successful, these new lamps to replace existing A-19, substrates could further advance R-20, R-30, R-38 and MR-16 the acceptance of LEDs into the bulbs. However, even with this lighting markets based on higher expected LED market growth, performance and lower chip challenges still exist for LED costs. Ben forecast that Inlustra luminaires, including bad press will bring 4-inch gallium nitride from poor quality and no warranty substrates to the market in 2013 early LED luminaires, LED product and that the market for these education, not enough standards, a- and m-plane wafers will grow improved warm-white efficiency from about 50,000 substrates in and potential competition from 2011 to 450,000 in 2015. other light sources such as plasmas. BritePoint, Inc., is also a venture startup founded to supply Recently, support has enabled a specialized LED lighting in the wide range of diverse LED- form of ‘extreme high brightness’ lighting support companies to be luminaires that can replace the funded. An example would be more than 250 million metal Inlustra Technologies, which is a halide fixtures presently installed 2005 spin out from UCSB, in North America. They are focused on the development of reported to form a potential $100 Hydride Vapour Phase Epitaxy billion plus market that requires processes for the production of replacement every 12-18 months. low defect density, large area, BritePoint luminaires are focused low cost, semipolar and nonpolar on high wattage lighting bulk gallium nitride device applications served by LED substrates. These a- and m-plane arrays that will replace halide gallium nitride substrates will sources, all with outputs higher enable the production of higher than 10,000 lumens. The brightness green LEDs, long a BritePoint LED replacements will weakness for the production of have 85% higher lighting more efficient LED green and efficiencies and teo to three times RGB sources of white, plus they longer lifetimes. Thus, the will also enable the efficient company’s E39-base lamps will production of R, G & B laser provide 70% savings and longer chips, especially green laser lifetimes over the metal halide diodes. Ben Haskell, Inlustra’s competition. Tom Griffin, the CEO, believes that the use of BritePoint CEO, is seeking a $10 these substrates will lead to a 10 million additional investment for a fold reduction in the cost of LED facilities expansion that will lumens combined with a much support ‘explosive growth’ for the improved and very small company to $100 million in three efficiency droop that enables high years and to $700 million in five. EVENTS STRATEGIES IN LIGHT - INVESTOR FORUM 28

Figure 1: efficiencies of 92 lm/W and 67 lm/W, Replacement lamps of different with a proposed high volume price of form factors, from $8/unit later in 2011. A19 over PAR to MR16m were also The second GaN/Si Company that is a hot topic at the shipping both high brightness LEDs Investor Forum (Img.: Courtesy of and power electronic chips is Azzurro Lighting Science Semiconductors AG a pioneer of this Group) technology and a 7-year old venture- backed spin out from Magdeburg University in Germany. It received its last round of funding of €14.5 million in late 2010 for new facilities and to add more reactors. Azzurro reports that it has solved the hetero-substrate epitaxy growth problems, including crack-free GaN (up to 9 microns thick) on 6-inch silicon, wafer-bows of less that 20 microns over 150 mm and A further advance in LED lighting This Investor Forum also heralded the dislocation densities comparable to technology was announced by Ventiva coming of age of gallium on silicon the widely used GaN on sapphire. The Inc, a private, Foundation Capital technology (GaN/Si) with two Company claims to have good IP backed, company located in Northern companies providing data on their protection and presently manufactures California. This small Company is a commercial GaN/Si LED chips already their GaN/Si chips on 6-inch silicon pioneer in the solid state cooling of on the market. One is the China-based wafers. Azzurro plans to have an LED replacement lamps, using their Lattice Power Corporation, a venture expanded MOCVD reactor capacity on ‘no-metal’ Ventiva Solid-State-FanTM funded company, with the CEO, Sonny line by mid-2011 and a scale up to (VSSF) technology. According to Carl Wu, also being a strong proponent of 8-inch substrates by the end of the Schlachte, Ventiva’s CEO, the the GaN/Si technology. At the meeting, year. Additionally, the Company offers Company is now sampling worldwide Sonny also claimed Lattice to be the GaN/Si GaN-epitaxy wafers and a line and has secured its first two fastest growing LED Company in of LEDs that can boast of a high customers. It will start shipping to the China and described their one watt breakdown voltages (750 V), suitable US and Asian markets in early 2012, LED GaN/Si chips that had been under for being driven directly from mains with their target product being the development since 2008 and that have voltages. 120V A-19 bulb type. The LED bulb been sold commercially since has the standard shape, but there is a mid-2010. Lattice uses both AIXTRON This Strategies in Light Session was a plastic shell on the Edison base and and Veeco MOCVD equipment for very good Investor Forum and superimposed on this (and under the GaN/Si epitaxy in a 120,000 square provided an excellent outlook for LED LEDs) is the VSSF that is claimed to foot production facility. The reported products and support in the general provide a constant 30°C-delta over the performance of these LED chips was lighting market, a picture that ambient temperature. The top part of 110 lumens at 5000 K, based on continues to improve!. the globe contains the 1600 lumen forward voltages in the 3.1-3.2 V Bridgelux LED package. In a sample range, operating currents of 350 mA comparison, Carl indicated that a and light efficiencies in excess of 50% Toshiba, 7.5 W LED A-19 provided 560 EQE. Lattice has strong support from lumens at a CRI of 65 (74 lm/W) the local government and is planning whereas a Ventiva-enabled A-19 used to add about 45 more MOCVD 31 watts, but had a directional output reactors in 2011 plus a scale up to of 1600 lm at a CRI of 80 and a 150mm wafers. The company also 52 lm/W efficacy. This is a better produces 120 V Edison base output than the 100 W incandescent 7 W-lamps for the residential market bulb and would be much more suitable that produce 700 lumens of cool or for residential buyers, with the 480 lumens of warm white light. These inference being that the VSSF bulbs were reported to have an technology provides a much smaller estimated 40,000 hour useful life and and lower cost alternative to the use of offer CRIs of 67 for cool and 80 for bulky aluminium heat exchangers. warm white output at respective

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LED Street Lighting - About Standards, Challenges and Misconceptions

Siegfried Luger and Arno Grabher-Meyer from LED professional discusses several street lighting issues with Prof. Dr.-Ing. habil. Tran Quoc Khanh from the Institute for Microtechnology and Electromechanical Systems at the TU Darmstadt, getting insights into European street lighting standards, the human light perception, some misinterpretations of lighting facts and the future perspectives of LED street lighting.

LED professional: First of all, thank so-called service and collecting road high. In these cases you can count on you very much for granting this where the illuminance is the luminous about a 30-40% visibility gain when interview with us. We'd like to begin quantity, for example S4 class with using LED lighting. Big streets with with the subject of standardization. 5 lx, and the other is the so-called over 1-2 cd/m2 have smaller and What are the current standards? public highway where the luminance is smaller gains and the values for twilight relevant. The higher the illuminance vision come close to the values for day Prof. Khanh: The EN 13201 has been and luminance is, the lower the vision. The norm values for public valid in Europe since April 2004. This is number of accidents and crimes. highways can therefore be seen as partly based on the DIN Norm, 5044 correct. that was developed about 30 years LED professional: Are similar ago and which was valid until about standards to the EN 13201 valid on LED professional: Does this mean a 2005. About 80-90% of the guidelines an international level? possible 30-40% energy savings for from DIN 5044 were carried over into service roads? the EN 13201. Prof. Khanh: In the USA and Japan, for example, completely different Prof. Khanh: Most people think that LED professional: Does the EN 13201 norms apply but the scale of permitted you can save energy by dimming the describe the different types of streets values are similar. light by 30-40%. This is not really and their requirements for correct because it depends on the illumination? LED professional: How does the way individual visual task. Let’s assume, for people see during the day and at example, that we want to be able to Prof. Khanh: First of all, the traffic night influence the development of recognize a person’s face so that in situation has to be determined. In street lighting? the case of a crime, a description of order to be able to classify a street one the perpetrator can be given. For this must first define how much traffic is on Prof. Khanh: That is probably the visual task the visual performance it and what the maximum speed limit biggest problem at the moment. All “visual acuity” is relevant, which means is. In addition, it also has to be defined norms, like for example, the EN 13201, that the white LED light doesn’t have if, for example, the street is a mix of use photopic photometric units like lux any advantages. If, however, we are bicycle path, walkway and roadway. and/or cd/m2 which are based on day talking about making a street look vision. This only begins at a luminance bright, a person perceives LED light as

LED professional: Light from different of 5-10 cd/m2. brighter and you can dim the light by light sources has various effects on 30-40%. The white light is the ability to see. Does the EN 13201 Generally, the research results can be advantageous because it means early cover these aspects or does it only summarized like this: For small streets, detection of objects or people that are address the general guidelines? like for example, service roads where moving at the side of the road. For 3-5 lux (about 0.20-0.50 cd/m2), is example, with LED lighting, object Prof. Khanh: In principle, this norm necessary, the advantage of white detection happens 1 to 1 1/2 seconds divides the streets in Europe into two emission, like, for example, from an earlier. In summary we can say the basic types. The first type is the LED or a mercury vapor lamp, is very following: An LED light can generally

Figure 1: The disadvantage is certainly the cost Relevant areas for the development of LEDs. Today the manufacturing of a modern street costs for an LED lamp is at about light 150-250 Euros which is the same as the sales price for a luminaire with conventional light sources. Even if you calculate the maintenance costs, you don’t get a return on investment for at least 10 years. It is precisely the dimmability that could improve the point balance considerably.

LED professional: Isn’t this a contradiction? Dim to reach the cost effectiveness of the LED lamp, but don’t dim because we have to orient ourselves on the state of the art and fulfill the visual tasks in roadway traffic competence. The color rendering is the applicable norms? better. Dimming is not an unavoidable also good enough and the dimmability scientific conclusion because dimming and/or shiftability are big advantages. Prof. Khanh: When we talk about means that certain visual tasks cannot LEDs are virtually dot shaped light dimming we must also look at the be fulfilled correctly. sources so that with optics (lenses, brightness control in twilight situations. reflectors) the light is projected exactly If the light is dimmed at night we would LED professional: From the point of in a targeted area. This cannot be really have a problem in an accident view of the standard, then, can we done with discharge lamps like situation. Dimming can be understood really carry out a night time shut off mercury arc lamps, sodium lamps or in another way. Imagine that there isn’t or a night time draw down? fluorescent lamps which are very big. any traffic at all on a street all night long. Why would you have to have it lit Prof. Khanh: That is a very important In a recent research project we 100%? Let’s think of an ideal lamp. and very hard question to answer. For compared the detection potential of Why shouldn’t the lamp concentrate economic reasons, it wasn’t possible road markings on the street at night, on the pedestrian if there isn’t any to dictate legally binding limit values in illuminated in the same conditions with traffic on the street? It is only with the the standard. Because the norm is not white LED light and with yellow sodium development of intelligent lamps that a legally binding regulation, a lamp light. The conspicuity of the road we can see even stronger advantages community can deliberately not adhere marking illuminated with the LED-light of LEDs in street lighting. to the standard. It becomes is much better. This is a very good problematic if a legal inquiry is made in argument for the reduction of traffic the case of a traffic accident because accidents. the standard has been formulated to coincide with the current state of the art, which means the responsible parties can be made liable.

LED professional: Generally, where do you see the advantages and disadvantages of LEDs in street lighting?

Prof. Khanh: As components, LEDs have a long life time if good thermal management has been taken into account and the construction of the electronic components has been carried out carefully. I have personally examined LED lights that failed after 5,000 – 7,000 hours. The reason was not the LED itself, but rather the implementation of the system which Figure 2: Efficacy of different LEDs dependant upon the dricing mode (PWM vs. was carried out with insufficient Constant Current)

LED professional: Let’s stay with the whereby the color temperature in both subject of dimming for now. PWM cases changed a little, though color dimming is thought of as the temperature with PWM dimming quasi-standard for LEDs. Yet, pulsed changed less. We therefore think that dimming can lead to miscalculations the analogue dimming method is quite of distances in connection with suitable for LED-street lighting. moving objects. What is the current research opinion here? LED professional: Right now the subject of renewable energy sources Prof. Khanh: We started researching is quite popular. How do you see the that about three years ago. Currently, combination of LED street lighting we are working on a research project with solar energy? from a large automobile manufacturer and the German government Prof. Khanh: We developed that type concerning this topic. of luminaire for a big German luminaire manufacturer. This subject must be The subject of dimming has been differentiated when looked at. Our Prof. Dr. Tran Quoc Khanh clearly underestimated. Older systems examinations showed that, for dim with, for example 100-200 Hz, example, the energy won from the sun Prof. Tran Quoc Khanh studied which alone can lead to irritations. in Germany could supply service roads technical optics and wrote a and parking lots but not public Ph.D-thesis on the field of the optical 3-4% of the population has problems highways. Of course, intelligent spectroscopy. After 17 years in the with modulation frequencies at this solutions can be applied here as well industry, in which he developed the level. There was the case of a person that monitor battery charges and then world's first digital cinema camera on that had to stop his car in a tunnel steer or dim the light accordingly at the principle of CMOS and a cinema because of the light modulation. The night. film scanner with LED-Chip on Board so-called Bailey’s beads effect is also technology, he came to the University known which is created by the LED professional: When using solar of Darmstadt, Germany in 2006. He modulated tail light and the turning of energy in street lighting it is is the chairman of the laboratory for the head when passing cars. practically always assumed that a lighting technology with the main battery will be used. How do you see fields in automotive lighting, street LED professional: We have a study using a hybrid system with the option lighting and indoor lighting using on hand that says that all irritations of being able to feed able to feed of LED-OLED technology. and miscalculations can be the AC-mains during the day? eliminated at 400-500 Hz. Do you agree? Prof. Khanh: We actually thought about that solution and are working on Prof. Khanh: At 300 Hz, 5% of the test it with the professorship of electrical persons could still feel the effects of engineering in Darmstadt. The LED the frequency modulation. At 500 Hz, professional Review (LpR) has an the statistics show that there were no international readership. For this more effects on the test persons and reason we had to think about the fact therefore there is zero risk. that countries in the south or even my native country, Vietnam, have enough LED professional: Wouldn’t it be sunshine to make solar lighting advisable, then, to go completely possible also as a hybrid version. away from PWM light and to use constant DC controlled light? LED professional: Thank you very much for this fascinating talk. Prof. Khanh: This subject is currently being examined, namely with red and Prof. Khanh: Thank you. white LED light. Our results show an efficiency increase of 30-60% in the case of analogue dimming in comparison to PWM dimming,

LEDs for General Lighting Solutions OSRAM Opto Semiconductors empowers lighting solutions for today and tomorrow APPLICATION DC MICROGRIDS 34

DC Microgrids and SSL - Key Components for Zero Net Energy Buildings

Brian T. Patterson, Chairman of EMerge Alliance and General Manager of Business Development at Armstrong World Industries, and Karen Lee, LC, LEED AP, Head of Applications Marketing at OSRAM SYLVANIA are giving an introduction in the aims of EMerge Alliance, standardization issues and the opportunities of LED lighting in combination with DC microgrids.

The quest for zero net energy effort we call the “Smart Grid”, nobody variable speed wind turbines that buildings is likely to change predicts this will solve the underlying natively produce DC power, making a great deal about the way and growing shortage of electrical power conversions a double negative! we approach designing and energy supply. The fact is we’re constructing buildings in bleeding electrons moving at the Our current 100-year-old electrical the future. From the use of a speed of light. Energy consumption, power system is full of similar broadened integration team like population, is growing faster than mismatches and power inefficiencies. in early planning and the conservation alone will satisfy. Today’s digital world needs DC power heightened use of BIM tools to at the device level. And if electricity the consideration of a diverse Some of that burden can be borne by storage is a factor, either to pallet of energy efficient building being smarter about how we use compensate for the non-dispatchable solutions and site-based power energy in buildings. It’s not rocket nature of most renewable energy generation and storage, the days science to understand that replacing sources or to back up critical mission of incremental improvement incandescent and T12 fluorescent functions like data centers and of older technologies may not lighting with T8, T5 and LED lighting emergency lighting, multiple meet the challenge. We need along with adding a few controls like conversions of the same original power to start changing the way we dimmers and occupancy sensors can is necessary. Could we find a better fundamentally look at power, and help. But natively direct-current (DC) way of wasting power? we need to do it now. powered LEDs increasingly used in the lighting of buildings gives rise to the However, nobody is suggesting we Traditionally, we have had a very troubling question, “how can we stop relive the Edison – Westinghouse battle generation-centric view of electrical the waste of power associated with of the currents. The tone is more power. But the current strain on these converting every watt of power for moderate and focused on hybrid systems collectively has resulted in an them from AC to DC?” Just as bad is systems, systems that minimize ever increasing number of critical that more and more of that power is conversion loss and improve overall supply mishaps. And although utilities generated locally by renewable reliability of the whole power system. are working hard to fix our problem, an sources like solar photovoltaic and This means change, real change in the way we deal with power at the building Table 1: level. To minimize the growing problem By introducing a DC grid of excessive power conversions in our energy saving power systems, we need to make opportunities greater use of native DC electricity in in various our power systems. By simply making applications are thoughtful and deliberate changes in given our systems over time, we can save an enormous amount of energy. And while we are at it, we can make LED lighting, and site-based renewable

Figure 1: EMerge Alliance occupied space standard system

power generation and storage easier and addressing the needs of this interface to enable shock and startle and more efficient to integrate. At the emerging technology, including hazard free plug-and-play device same time we can also increase user catalyzing the development of a robust flexibility. In all cases, the standards safety, provide low cost plug-and-play supporting commercial eco-system are being crafted to facilitate energy reconfiguration flexibility, and and coordinating the review and savings at all levels by avoiding fundamentally improved equipment revision of existing code and regulatory unnecessary power conversions and and system reliability. treatments with the help of maximizing the opportunity for highly organizations like Underwriters Labs, articulated digital control. But widespread use of DC will not NEMA and NFPA. happen automatically – the impediments to deployment need to The Alliance’s collective vision is to LED Lighting and DC be dealt with at a variety of levels and create new, open standards for Power Microgrids from a number of perspectives, not the room- and building-level DC As we strive to create LED systems least of which is the creation of microgrids for commercial buildings that are well suited for general lighting application standards. To help that include the occupied space, data applications, we find that the organize this effort, an open industry, and telecom centers, building services performance and technical parameters nonprofit organization called the and utilities, and outdoor power, of collateral components, as well as EMerge Alliance was founded by including plug-in electric vehicle the systems that feed them, are just as companies like Johnson Controls, charging. The standards are targeted critical to the overall solution as the OSRAM SYLVANIA, Nextek Power to complement the existing AC LED itself. As the efficiency of LED Systems and Armstrong World infrastructure and standards with a chips continues to improve at the rate Industries. These pioneers have been hybrid DC power layer at the of Moore’s law, or doubling efficiency joined by companies including Philips generation, storage and device load every 18-24 months, more attention is Electronics, Emerson Network Power, level. focused on the other parts of the Watt Stopper/Legrand, Tyco system and the performance expected Electronics, Cooper Industries, Acuity The proposed EMerge standards from a lighting perspective. If we Brands, Crestron, Hubbell, Leviton, define safe low voltages (under 600 remind ourselves first why LEDs are so Steelcase and a steady flow of other volts) for general power distribution interesting for general lighting companies and organizations willing to and heavy plug loads and limited applications, it will not be difficult to help. These forward thinking current potential very low voltage (NEC see how DC power operation can companies are aggressively assessing Class 2, under 30 volts) at the user compound the benefits.

Figure 2: bi-level switching is used in more Example for the Zero Net Energy applications, this issue will become of Buildings - increasing interest. From a design building level perspective, as well, the ability to offer DC microgrid varied light levels or dynamically with renewable changeable color broadens the and alternate distributed creative palette even further. generation feeds This bold new world, however, does not come without its challenges. While initiatives such as the Zhaga Consortium are trying to add some order to this exploding new lighting portfolio, the fact is that limited standards and industry guidelines are available. There is no accepted counterpart to the familiar medium screw (E26) or the bi-pin base/socket combination. There are mounting holes LED technology has become the With LED technology, the expectation spaced –well -somehow. There are darling of the lighting industry because is that fixture designers will harness connectors that are available today, if of the promise to drastically cut energy the native directional nature of LEDs you can figure out who made them. consumption, particularly in and produce luminaires that have near With a technology that is advancing at commercial buildings. As energy perfect utilization of the light that is such a rapid rate, the issue of being codes and programs such as LEED produced, guiding each and every able to replace or upgrade LEDs in the become increasingly more stringent, lumen along the most direct path to future to repair early failures, change lighting power density restrictions the task at hand. With efficient optical color or beam spread, or take become more challenging to meet systems, the need for large reflectors advantage of improved efficiency, – particularly if good quality lighting or refractors should be minimal, becomes an extremely difficult and design is to be maintained. According thereby reducing bulk and cost and worrisome task. While some to the DOE, lighting can consume up increasing design flexibility. manufacturers have developed their to 30 percent of all electricity in own connector systems for commercial buildings. Part of the Beyond energy efficiency, the unique replaceable modules, they are not energy savings will come from the form factor of LED technology brings universal, so an installation would be efficacy of the LED itself. Compared to an entirely new dimension to limited to that one company if a the incandescent lamp that offers a architectural design flexibility. Gone are complete luminaire replacement was mere eight lumens for each watt of the size limitations of fragile glass not an option. power consumed, today’s premium packages wrapped in fixture reflectors LEDs can offer 10 times that amount, or refractors. Small, rugged LED Considering the opportunities LED when operated in a well designed packages may be arranged in endless technology can offer to the design, environment – or up to 20 times that configurations and be regarded as aesthetics, operations, and amount in perfectly controlled building materials rather than utilitarian maintenance of building, all can be laboratory conditions. That’s a good providers of visibility. Build lighting into positively impacted by the adoption of start, but not enough to surpass the floors, walls and furniture? Make light DC power grids as a component of the lumens per watt performance of appear as if it comes from nowhere? overall building infrastructure. At the today’s best fluorescent lighting Why not? luminaire level, locally available DC systems that dominate commercial power eliminates the need for a power building spaces. Why all the fuss then, Another intriguing aspect of LED supply to convert the AC line voltage to you may ask? technology is the relative ease with be usable by the LED devices, which which it may be controlled. There are results in one loss mechanism and The other aspect to consider in the no warm-up time or hot restrike issues improves efficiency of the fixture by up energy efficiency story is the efficiency to mitigate, making operation on to 15 percent. Multiply that savings by of the luminaire. It does no good to occupancy sensors a natural fit. As the number of lighting fixtures and generate light very efficiently if it gets semiconductor devices, LEDs are well other electronic devices in a building, trapped in the fixture and never makes suited to extremly low temperatures, and the savings can be quite it to the task plane to actually provide making them ideal for applications in significant. For sites that have on-site illumination. For some of the most many outdoor or uncontrolled renewable energy sources, yet another common luminaire types used, troffers environments. As building codes and DC-to-AC power conversion step, with and down lights, for example, fixture best practices move to requiring its associated losses, is avoided. As efficiency can be as low as 60 percent. control systems and dimming or as luck would have it, many of those

electronic components eliminated in without the need of shutting down the Using “Smart” DC that front-end conversion are those entire circuit, a technique called Microgrids responsible for limiting the life of LED “hot-swapping,” and the fixtures do not According to the Zero Energy systems today, so overall system require separate high-voltage Commercial Buildings Consortium final reliability improves as an added bonus. disconnects. Where the task is simply report [1], “DC microgrids would In many cases, it is not the light- troubleshooting or repairing a single fundamentally change the way power emitting diode that fails in the system, fixture, safe and speedy maintenance is supplied in commercial buildings, but the power supply or other can take place without disruption to eliminate AC-DC conversions at the electronic component responsible for normal business operations. If you are equipment level, simplify equipment controlling performance. a property manager welcoming a new designs and layouts, provide improved tenant or a business accommodating a interfaces with renewable energy From a building operation and new working group, this capability can sources and storage, and save maintenance perspective, the benefits be a very welcome change that energy.” of DC power grids go beyond represents valuable time and labor decreasing energy consumption to savings. reducing labor costs and business That’s because DC microgrids interruptions. With a distributed power EMerge standards for the occupied can provide for the following: grid bringing low 24-volt DC power space call for very low, touch-safe • Energy Savings – while the amount throughout a space, several safety and voltages. With traditional and/or of savings in electrical energy is maintenance practices become much home-run wiring conventions, this somewhat difficult to completely easier. When a need to change normally results in a concern for power capture, a Yale published research furniture or traffic patterns in an area loss in the resultant long wiring runs. estimate [2] puts the annual potential arises, a modification in the lighting But the unique wiring topologies of the reduction at more than eight percent design often comes with it. This might standard address this concern by of the total national electric load, or typically require significant rewiring or using a “hub and spoke” wiring approximately 400 million kWh per new circuits and re-commissioning of method that inherently shortens any year. This does not take into account control systems by skilled electricians, given wiring run. The standard additional energy savings as a result including provisions for temporary specifically limits individual spoke of less cooling being required in lighting while the system is being lengths to avoid this situation. The buildings where fewer electronic reconfigured. With a DC power grid power hubs feeding power to the conversion devices are used. based on the EMerge standards, electrically isolated spokes are however, the pluggable busses are strategically distributed throughout the • Renewable Energy Integration already distributed throughout the space. Each hub is wired to higher – DC microgrids facilitate simple and space and only a physical voltage AC and/or DC distribution with more energy efficient coupling reconfiguration of fixtures and software even less loss. This feed layer in the (eliminating the need for multiple reprogramming would be required, grid topology can use existing building inverters/converters) of distributed particularly with the wireless control wiring or can involve new wiring as alternate and renewable energy systems available today. Additional or part of the building’s DC microgrid, generators (solar, wind, fuel cell, etc.) upgraded fixtures may be easily added which combines the direct on-site use that natively produce DC power. without new wiring, since power would of renewable and alternate energy Industry sponsored research [3] at be drawn from the electrified ceiling sources. the Electric Power Research Institute grid already in place. At this low (EPRI) has concluded that multiple voltage, luminaires may be relocated distributed source generation

References: coupled onto a common DC bus Proponents of DC microgrids, [1] http://zeroenergycbc.org/pdf/ can simplify and make more efficient including members of the EMerge CBC%20Technologies%20 the use of site-based alternate Alliance, believe they can provide a Report%202011.pdf energy. new dimension of utility and efficiency [2] http://environment.research.yale. to improve our electrical energy edu/documents/downloads/0-9/05- • Energy Storage – Local energy system. They further maintain that they DC-Microgrids.pdf storage will be essential to the are a critically needed addition to the [3] http://www.emergealliance.org/ widespread use of non-dispatchable work and goals of the current smart imwp/download. distributed energy generators. The grid overhaul. DC microgrids hold the asp?ContentID=19276 distributed bus architecture of DC potential to change the paradigm of a [4] http://www.emergealliance.org/ microgrids allows simple and more centralized power generation and imwp/download. energy efficient coupling of natively distribution system to one more akin to asp?ContentID=19272 DC (batteries, Ultra capacitors, etc.) the distributed network configuration electricity storage. of the Internet. As such, we could expect it to be more flexible, • Control & Monitoring – Most accommodate greater innovation and modern controls, sensors and generally be more accommodating of monitoring systems natively run on the power sources and loads that have DC current and are digitally and/or come to be and will continue to microprocessor based [4]. The use develop. of DC microgrids therefore greatly simplifies the electronics involved with electrical and energy system About the EMerge Alliance control and monitoring by eliminating The EMerge Alliance is an open the need to convert AC power to industry association leading the rapid operate. adoption of safe DC power distribution via DC microgrids through the • System Reliability – The intrinsic development of EMerge Alliance redundant, disaggregated topology standards. of DC microgrid networks assure a higher level of basic service reliability. By being ‘islandable’ both public grid and the individual microgrids can be isolated from one another during other dynamic and damaging linear failure events and disturbances. The reduction in subsystem and device-level power conversion/inversions generally improves ‘mean-time-to-failure’ levels in the equipment. Figure 3: The vision for DC microgrid • BEV/PHEV Integration – As electric throughout buildings vehicles begin to populate our national automotive fleet, plug-in These innovative standards integrate charging and their potential use in infrastructures, power, controls and providing supplemental storage or devices in a common microgrid electricity back-up capability, electric platform to facilitate the hybrid use of power grids will increasingly need to AC and DC power throughout accommodate this shift in energy buildings for unprecedented design distribution and use. Since these and space flexibility, greater energy vehicles run on pure and modulated efficiency and improved sustainability. DC electric systems, DC microgrids The nonprofit Alliance is accepting new will more easily provide for their members at various levels. charging (including fast DC charging) and storage connectivity needs, again with fewer wasteful power conversion/inversion steps.

ELECTRONICS DIGITAL SIGNAGE DRIVER 40

LED Driver Innovations for High-Performance Signage

Toshiba’s Marketing Manager for Consumer and Industrial ICs, Roland Gehrmann explains how new generations of driver ICs are overcoming challenges of today’s large LED signs, where many thousands and sometimes millions of LEDs, often arranged in groups of red, green and blue that act as a single pixel.

Figure 1: Designers of digital signage Multi-channel are taking advantage of the LED control via increasing performance of microcontroller serial interface high-brightness LEDs to tackle ever more ambitious projects. Today’s large LED signs can contain many thousands and sometimes millions of LEDs, often arranged in groups of red, green and blue acting as a single pixel. Large LED arrays such as these, present tougher and more wide ranging control challenges compared to small-scale signage or backlighting applications. The brand new generations of driver ICs, which are subject of this article, are overcoming these challenges.

required. Close matching of driver closer matching between channels Extra Channels: Extra output current - from channel to and drivers allows designers to achieve Challenges channel, and from driver to driver acceptable optical performance with Figure 1 illustrates how a multi-channel - becomes extremely important when lower-cost LEDs, which can have a driver is used to supply constant designing very large LED signs. relatively broad spread of parameters current to a group of LEDs, receiving from device to device. high-level command signals from the host system microcontroller. Drivers Enhancing Visual Impact LED output power continues to with eight, nine or sixteen channels are Channel-to-channel current matching increase with improvements in typical today, and 24-channel devices to within ±3-6% has traditionally been current-handling capability. At the will become commonplace in the adequate for many applications. same time, signage designers strive to future. Even so, several thousand However, as signage dimensions grow, create larger, brighter displays drivers may be needed to control the driver ICs targeting large multi-LED providing greater effective viewing entire LED array in a large signage applications must deliver greater range. As a result, suitable drivers solution such as stadium advertising or precision. The 16-channel Toshiba must be capable of supplying higher a public noticeboard. TC62D722 driver, for example, has maximum output current. Drivers must channel-to-channel matching to within also be able to maintain close control LED brightness and emitted ±1.5%. Importantly, IC-to-IC output over driving current as the output wavelength vary according to supplied matching is also within ±1.5%, which voltage to the LED varies. The current. For this reason, constant- gives designers extra confidence to TC62D722 has output adjustment current drivers are the preferred create large-size displays with high range from 1.5 mA to 90 mA, with a solution in large multi-LED applications pixel density and requirements for flat current characteristic over a wide where consistent optical output is large numbers of driver ICs. Moreover, output voltage range (Figure 2).

Figure 2: Improved constant- current drive characteristic for high-power LEDs

Simplifying Power issues in a large display panel has Design typically involved the use of large Integrated output delay is another numbers of external components feature assuming greater such as capacitors to flatten importance in the context of spikes and damp oscillations. ultra-large LED signage. In a large Newer generations of multi- display it is normal to connect the channel drivers for high-output drivers controlling blocks of up to signage applications, however, 64 LEDs to one power supply have integrated circuitry to and switching on a large combat switching noise. This proportion of these LEDs reduces the need for external simultaneously imposes high components, which simplifies peak demand. The worst case design and assembly, reduces would be if all the LEDs in a cost and improves overall multi-million LED display were reliability. switched on simultaneously; this would call for a relatively large and expensive power architecture Solving Flicker capable of supplying a very high In dimmable signage where peak demand. animations or frequently changing images are displayed, the One way to prevent sudden, large dimming PWM output cycle must current fluctuations is to be fast relative to the image implement edge-rate control for update rate. Consider a each channel. This limits the dimmable driver with 16-bit change in current as the outputs dimming resolution. If a PWM are enabled or disabled. clock frequency of 30 MHz is Alternatively, the output-delay applied, the PWM output rate technique automatically inserts a would be 458 Hz. If moving short time period to stagger the images are to be displayed, this turn on of each channel. This frequency is close enough to the reduces the peak power demand image update rate to produce a per driver, reducing power surges noticeable flickering. Increasing and allowing the use of smaller, the clock frequency to raise the lower cost, power supplies. PWM output rate would increase noise, power and thermal issues, as well as cost. Noise Abatement Switching of large numbers of A new Division PWM technique LEDs also tends to generate effectively increases the PWM noise and ringing on the output rate without an attendant channels. This can interfere with increase in clock frequency. With the driver’s own circuitry, and that Division PWM, given the same of adjacent drivers, as well as 30 MHz frequency and 16-bit presenting EMC compliance dimming resolution, the 2.18 ms challenges. Addressing these PWM output cycle (1/458 Hz) is ELECTRONICS DIGITAL SIGNAGE DRIVER 42

Figure 3: open-circuit or short-circuit failures in Division mode PWM combats individual LEDs throughout the array. flicker in dimmed Where several LEDs are connected in signage displaying series as a string, a single open- moving images circuit failure can result in the entire string failing. Sometimes, failsafe shunt devices may be fitted to bypass an LED in the event of an open-circuit failure and so allow other LEDs in the string to continue operating. Integrating protection features within the driver IC saves external components and can allow the type of fault and its location to be communicated to the controlling application. divided into 128 sections each A multi-channel driver designed for corresponding to 512 clock cycles. signage applications may typically In the TC62D722, two internal The PWM duty cycle needed to draw a few milliamps in its quiescent comparators are implemented at achieve the selected dimming level is state. In a large display comprising, each output, to detect the effect of a replicated within each division period, say, 1000 drivers operating at 5 V, short- or open-circuit LED on the effectively increasing the PWM output this translates into a total power drain voltage at the output pin. The status rate from 458Hz to 59kHz and so of 35 W, even when no LEDs are lit. of the open- and short-circuit eliminating the problem of flicker With this in mind, the use of power comparators is recorded in an when displaying moving images. management modes is likely to internal shift register, allowing the become commonplace in LED driver to indicate the exact nature of Division PWM is particularly suited to signage designs of the future. an LED fault via its serial data output drivers like the TC62D722, since this pin. Thermal shutdown protection device does not use output edge-rate To support power management in and a power-on reset function are limitation to combat switching noise. energy-conscious applications the also provided. The device also supports normal TC62D722 provides a standby mode. PWM as well as Division PWM The mode is controlled from the modes. These are set using an application software by setting a bit in Conclusion internal register, and the driver also an internal register, and reduces the High-brightness LEDs for signage permits setting 16-bits, 14-bits, IC’s current draw to below 1 µA. This and lighting have been adopted 12-bits or 10-bits PWM resolution. could enable designers to reduce enthusiastically for use in a variety of Figure 3 illustrates Division PWM quiescent power consumption of up environments. While simple LED compared to normal PWM operation to 35W, in the example discussed drivers using principles established in the TC62D722. earlier, to a standby Figure of 5 mW, with low-output indicator-type LEDs realising benefits both in terms of will continue to be used in numerous energy usage as well as the cost and roles, more advanced applications Power Management sizing of the power architecture. require new approaches and greater As the size and performance of LED feature integration. High-performance signage products continue to signage incorporating thousands or increase, power management within Improving Diagnostics even millions of high-brightness LEDs the LED driving subsystem is growing Error reporting including identification are among the most demanding of in importance. High energy prices are of faults such as LED failures is these. Small improvements to causing signage buyers and especially important in LED signage aspects such as power management operators to consider power applications where extremely large and noise reduction are already consumption as part of the decision numbers of LEDs are used. Although enabling system performance to making process. Power-hungry LEDs are known to have long move up to the next level. signage is also unattractive to lifetimes compared to incandescent organisations focusing on reducing bulbs, factors such as vibration and their carbon footprint. high temperatures can produce

High Brightness LED Drivers with High-Side Current Sense

D D VIN

VIN L RCS RCS L CIN LED1 LEDN LEDs

CIN

CS LX CS DRV

RG VIN PGND VIN EP MIC3202 MIC3203 EN VCC EN VCC CVCC CVCC DIM DIM AGND PGND AGND

Applications

Landscape Lighting MR-16 Bulbs Architectural Lighting

The rapid growth of LED lighting applications in Ideal for use in: commercial, industrial and automotive markets has led  12V Lighting Systems (MR-16 Bulb, Under Cabinet Lighting, to a wide variety of technical challenges for LED Drivers. Garden/Pathway Lighting) Micrel is meeting these challenges with simple  Architectural, Industrial, and Ambient Lighting step-down LED Drivers such as the MIC3202 and MIC3203.  LED Bulbs The MIC3202 is a hysteristic step–down LED Driver  Indicators and Emergency Lighting with integrated MOSFET capable of driving up to  Street Lighting 10 HBLEDs with constant currents up to 1A in a  Channel Letters thermally enhanced exposed pad SOIC-8L package. The MIC3203 is a hysteristic step–down LED Driver with an external MOSFET capable of driving up to 10 HBLEDs Part Input Output PWM Dithering Package with power levels up to 40W in a SOIC-8L package. Number Voltage Current Dimming MIC3202 6V to 37V 1A Yes Yes EP SOIC-8L For more information, contact your local Micrel sales MIC3202-1 6V to 37V 1A Yes No EP SOIC-8L representative or visit Micrel at: www.micrel.com/ad/ leddrivers. MIC3203 4.5V to 42V Controller Yes Yes SOIC-8L MIC3203-1 4.5V to 42V Controller Yes No SOIC-8L

LED Professional_Mar-Apr11.indd 1 2/16/2011 10:57:55 AM THERMAL ACTIVE COOLING RELIABILITY 44

LED Cooling in Harsh Environments with Synthetic Jet Technology

Dr. Markus Schwickert, Director of Reliability and Brandon Noska, Application Engineering Manager at Nuventix discuss different reliability issues of active cooling. Test procedures and results to prove longevity of sophisticated active cooling systems are presented.

Lighting is rapidly transitioning compact in order to fit into existing in the medium for cooling. When these from traditional lamp sources sockets. In all cases, if a reliable jets are directed at heat sink surfaces, such as high-pressure sodium, technology for forced convection they remove the heat much more metal halide, mercury vapor, and cooling was available, designers would efficiently than natural convection fluorescent to high brightness have more options to provide the [2,3,4]. light-emitting diodes (HB proper lumen outputs while having LEDs). In fact, illumination was small, lightweight designs. the second fastest growing application for HB LEDs in 2009, Industrial and outdoor applications with a growth rate of 28.6% over pose other challenges in addition to 2008, and this trend shows no the thermal management signs of slowing. Architectural requirements. Components need to be lighting, combined with rugged in order to operate properly commercial/industrial sectors and to survive the elements. Although and the outdoor sector, account traditional air movers such as axial fans for 54.3% of the illumination could provide an adequate forced market [1]. convection thermal solution, this article will focus on synthetic jet cooling Along with general illumination technology, which is an alternative air products, LED outdoor lighting needs moving technology for forced proper thermal management in order convection cooling. This article looks Figure 1: Synthetic jet engine with to utilize the many advantages of LEDs at synthetic jet technology as a rugged oscillating diaphragm such as a long L70 lifetime, instant on, and reliable forced convection cooling better optical control, and, most solution that could be used in harsh Synthetic jets can be generated in importantly, low maintenance and environments to ensure effective many ways, but one mechanism is the reduced energy usage. Outdoor thermal management solutions. use of electromagnet actuators which products cover a wide range of create the driving force for oscillating installations including wall washing, the membrane. As the membrane parking lot, area lighting, roadway Synthetic Jets oscillates within the cavity, synthetic lighting, and garage lighting, to name a Although synthetic jets have been jets are created at the nozzles that are few. Some of these form factors have known and researched for many years, around the cavity. There are many enough surface area to allow for synthetic jet products are relatively advantages to using electromagnetic effective natural convection cooling, new to the market. Synthetic jets are actuators including no moving parts in but pose other issues such as weight formed by creating a periodic suction friction, no lubricants, and no bearings and large surfaces which are not good and ejection of fluids through an orifice to wear out. These inherent design for shipping, handling, installation, and generated by an oscillating diaphragm differences between synthetic jets and wind loading. Other form factors such in a cavity surrounding the diaphragm. traditional air movers such as fans and as retrofit lamps are bound by existing The jets are “zero-mass-flux,” thus blowers are what differentiate these infrastructure and need to remain there is no need for ducting or piping products in terms of ruggedness and

Figure 2 / Table 1: Natural convection versus forced convection. The table shows comparison data for natural convection versus forced convection

Figure 3: Evluma’s 40W LED Clearlight Natural Forced Metric Improvement Convection Convection Although the use of forced cooling has Form Factor Volume, cm3 5640 1400 75% many benefits as listed above, there Weight (kg) 3.0 1.4 53% are several elements that need to be Thermal performance θsa, C/W 0.25 0.2 20% considered for outdoor lighting. Typical requirements include IP 55 for electronics and other components, lifetime. The main failure mode of fans The forced convection coolin provides IP 67 for optical compartments, ability and blowers is lubricant breakdown. a 20% reduction in thermal resistance to withstand wash downs, to be This does not exist in synthetic jet resistance (qs-a), with a 75% reduction cleaned, large temperature extremes, products [5,6]. in volume and 53% reduction in vibration due to wind loading and weight. roadway vibrations. An effective outdoor LED light requires Benefits of Forced Cooling The Evluma 40 W LED replacement components that can withstand such Synthetic jet cooling allows for smaller lamp / luminaire for outdoor NEMA elements. Synthetic jets offer a rugged form factors, lower operating Type 5 fixtures is an example of a and reliable solution. Synthetic jets are temperatures, and dynamic airflow synthetic-jet cooled product available typically tested against high temp/high control for effective temperature on the market today. This product humidity, shock/vibration, dust, and control of the LED heat sink. replaces existing mogul base power cycling [8]. 50-175 W mercury vapor or 70-150 W Synthetic jets have been shown to high pressure sodium lamps. Evluma’s The next sections highlight the various have higher Nusselt numbers, hence 40 W LED lamp is an example of a testing that is conducted on synthetic higher effective heat transfer, over product that utilizes forced cooling to jet devices and the importance of this conventional ducted flows by a factor dissipate 40 W, while keeping the form testing: of six or greater at the same channel factor small for retrofit applications. Reynolds number. In addition, when comparing the thermal resistance of a

heat sink (θs-a ) cooled by synthetic jets or ducted flow at the same volumetric flow rate, synthetic jets have demonstrated as much as a 40% improvement in thermal performance. When compared to natural convection, synthetic jets have demonstrated 300% thermal improvement with the same form factor heat sink [7].

The higher heat transfer capability at low flow and significant improvement over natural convection is due to the turbulent vortex dominated jet flow which enhances the mixing of the thermal boundary layer and allows for improved thermal performance. For example, Figure two compares a 100 W design with forced convection cooling and natural convection cooling. Figure 4: Annual average temperature map, source Wikipedia.org

Reliability As a result, the latest SynJet family of Cyclic Condensing Humidity The local environment of a cooling products, synthetic jets Very hot and humid conditions are not solution in an outdoor light fixture commercialized by Nuventix, has as realistic as cyclic humidity depends very much on the eliminated all structural adhesive joints, conditions with condensation which construction of the enclosure and the and all materials and components can be achieved by cooling a device location and orientation of installation. must pass a 60 hour autoclave test and then subjecting it to warmer, Earth atmospheric temperatures (Highly Accelerated Stress Test, HAST) humid air (similar to taking a water typically range from -40°C to +40°C at 123°C, >95% r.h. and 2 bottle out of a refrigerator which will and can reach over +55°C in extreme atmospheres pressure. typically condense a lot of water from a conditions. Variations occur in day/ sufficiently humid atmosphere). During night cycles and throughout the With input from numerous customers the morning hours in most outdoor seasons while the relative humidity (r.h.) who inquired about outdoor usage, environments, depending on heat can range from nearly 0 to 100%. Nuventix has developed a platform- capacity and heat conduction of an based comprehensive qualification test object, condensation will be found on Furthermore, pollution (e.g. acidic matrix for synthetic jet products that its surface. Repeating this process atmospheres, pesticides, cleaning helps in predicting long-life with subsequent drying 200 or more solutions, building materials), ozone, performance under all realistic times in a laboratory environment will UV light, and naturally occurring conditions, some of which are bring out material and design substances in the atmosphere discussed below. weaknesses associated with (e.g. dust, pollen, insects) will interact condensing humidity. with light fixtures and may reach internal components such as the Freezing Rain Cycle Test LEDs, electronics, drivers and cooling This cyclic test is designed to address HALT solutions, impacting functionality or the repeated wetting and freezing of a Highly Accelerated Life Testing uses a lifetime. Generally, harsh environments product. In an environmental test combination step stress method to can not only be found outdoors, but in chamber the test starts at standard determine the margins of operation for some industrial settings or specialty ambient temperature (+25°C) with a product and highlights weak links in applications (e.g. aquariums, >95% r.h. followed by a sudden drop a design. Stressors include cold and commercial kitchens, automotive etc.) to ‑10°C to condense water on the unit hot thermal stress as well as as well. and freeze it. After 10 minutes of mechanical vibration stress. Table 2 freezing the unit is powered on for five shows an example of SynJet limits as Even ratings for ingress protection (IP) minutes and then operation is determined by HALT. will not reveal how the lifetime of a validated. This is repeated a minimum product is affected by harsh of 100 times. environments, but rather testify to its Qualification Matrix safety and ability to function under Table 3 shows a summary of tests that those conditions in the short term. Thermal Cycling were done and passed with the latest Here we focus on the cooling solution Thermal cycling, besides exposing the synthetic jet family of products. of a luminaire which must exceed the materials to a wide temperature range, Besides conditions, Table 3 also lifetime of the LEDs by far so that it addresses designs with mismatched indicates the sample size that was contributes positively to the overall coefficients of thermal expansion (CTE) used in the test. lifetime of the luminaire via extension of and stresses joints and material the LED lifetime, and does not limit it properties. By going 200 times or further [9]. more between -40°C and +105°C, Conclusion soaking for an hour at each Forced convection cooling can offer Given the unique requirements for all temperature and ramp rates of 5°C/ smaller and lighter weight designs different products and environments, minute with no failures allowed, this while maintaining the proper thermal there is no standard or set regiment of test adds to the confidence needed for management needed to keep HB testing that can guarantee outdoor a robust product in harsh conditions. LEDs within their design parameters. suitability across the board. Moreover, Synthetic jet technology is an air- a robust product with reliability moving technology for forced designed in must be measured up to Humidity convection cooling that is inherently the intended usage environments from The effects of high temperature and reliable and rugged due to a the early design phase through the high humidity can be surprising. Two construction that does not have production release. A thorough review major areas are affected: plastic moving parts in friction or require and qualification of the material degradation and metallic bearings or lubricants. Synthetic jet subcomponents, materials and even corrosion. All synthetic jet types are products are subjected to a rigorous processes used in manufacturing is a tested for a minimum of 2,000 hours at qualification program to ensure the must when designing for reliability. 85°C and 85% r.h. with no failures products are robust and can handle a allowed. wide application space.

Figure 5: Finally, there is no exact test that can Synthetic jet undergoing predict performance and reliability freezing rain cycle under all environmental conditions for test every conceivable luminaire design. However, by simulating worst case specific environmental conditions that occur during the expected life of an HB LED light and using accelerated stress tests for anticipated failure modes one can gain confidence in applications in harsh environments.

References: [1] Strategies Unlimited, “High- Brightness LED Market Review and Forecast 2010”, pp. 78- 83, June 2010 [2] Lasance, Clemens J. M., Aarts, Ronald M., “Synthetic Jet Cooling Part I: Overview of Heat Transfer and Acoustics”, 24th IEEE SEMI-THERM Symposium, 2008, pp. 20-25, 2008 [3] Mahalingam, R., N. Rumigny, A. Glezer, "Thermal Management Using Synthetic Jet Ejectors", IEEE Trans on Components and Packaging Table 2: Summary of Operating and Destruct Limits HALT operating Technologies, Vol. 27, No. 3, pp. Stress Type Chamber Setpoint Level and destruct limits 439-444, 2004 Temperature Lower Operating Limit (LOL) -60°C [4] Mahalingam, R., A. Glezer, "Design Temperature Lower Destruct Limit (LDL) < -100°C and Thermal Characteristics of a Temperature Upper Operating Limit (UOL) +120°C Synthetic Jet Ejector Heat Sink", Temperature Upper Destruct Limit > +130°C Journal of Electronic Packaging, Vol. Thermal Transitions (°C) Greater than +50°C/minute Vibration Operating Limit (OL) 45 Grms 127, pp. 172-177, 2005 Vibration Destruct Limit (DL) 45 Grms [5] Mahalingam, R., S. Heffington, L. Combined Operating Limit (OL) 60 Grms and 115°C to -60°C Jones, R. Williams, "synthetic jets for Combined Destruct Limit (DL) 65 Grms and -60°C forced air cooling of electronics", Electronics Cooling, Vol. 13, No. 2, 2007 Table 3: Cat. Test Operating Conditions Samples [6] Tian, Xijin, "Cooling Fan Reliability: The qualification 60 hours at 123°C, 96% r.h., HAST no 3 Failure Criteria, Accelerated Life 2 atmospheres matrix shows a Testing, Modeling and Qualification", summary of tests Storage Low Temperature no -40 °C 11 Annual Reliability and Maintainability including the Accelerated Life Testing yes 3,300 hours at 105°C 540 9,000 hours at 85°C, ongo- Symposium, 2006, pp. 380-384, sample size Life Testing at max normal yes 75 ing 2006 Low Temperature yes -40°C 87 [7] Noska, B., Che Cheung Jin, H. Humidity yes 85°C/85% r.h., 3,250 hours 60 Mahalingam, R., “Enabling new LED

Operational Thermal Cycling yes -40˚C - +105˚C, 200x 60 designs through advanced cooling 5-150 Hz, 2G 3 sweeps Sine Sweeping no 18 per axis technology”, Semiconductor 10 min each top of three Thermal Measurement and Sine Dwelling no 18 peaks, 5 G Management Symposium, 2010, Random Vibration yes 2.2 G , 20 min. each axis 18 rms SEMI-THERM 2010. 26th Annual Six half-sine shocks per Shock no 18 direction, 40 G, 11 ms IEEE, pp. 305-310

Mechanical Bump Test - 1,000 shocks, 25 G, 10 ms 18 [8] http://apps1.eere.energy.gov/ Dust yes 12 hours IEC 60529 (IP5X) 4 buildings/publications/pdfs/ssl/ 200 cycles between +50˚C outdoor_area_lighting.pdf / >95% r.h. and +5˚C / 5% Cyclic humidity yes 22 r.h., such that condensation [9] Schwickert, M. M., IEEE Transactions occurred on Reliability, pp. 449-482, Volume 100 cycles between +25˚C / Freezing Rain Cycles yes 21 59, Number 3, September 2010 Environmental 95% r.h. and –10˚C / u.c.r.h.

Thermal Management of LED Lamps

A.Motoya, M. Kai, Y. Manabe, and S.Shida from Panasonic Corporation Lighting Company show what measures can be taken to fulfill the requirements for LED replacement lamps, and which of these measures have the greatest impact.

Because of global environmental The structure of the LED lamp is In this paper, to investigate the proper pressure, people all over the explained in the following procedure: thermal management structure for LED world have started replacing The LED chip is mounted on the board lamps, the following three steps have conventional types of lighting and then it is sealed with the resin that been reported by means of a CFD with higher efficiency light is mixed with phosphor. This is called model. sources. In Australia and the EU, an LED module. When electric power governments announced that the is loaded, approximately 30% of input First, the design concept was made sales of traditional incandescent power is converted to white light and according to the desired lamp lamps would be prohibited 70% is converted to heat [1]. specification targets. Second, the starting in 2010. bottle neck elements of heat Excess heat directly affects both dissipation were determined, and the Conventional light sources (fluorescent short-term and long-term LED thermal phenomena analysed. Third lamps, halogen lamps) have improved performance. The short-term effect is the design parameters of the bottle over the past 30 years. On the other luminous efficacy and the long-term neck elements were calculated. hand, white LED (Light Emitting effect is accelerated lumen depreciation Diodes) has improved rapidly over the and thus shortened useful time. past 10 years as shown in Figure 1. Thermal Management of

Three things affect the Tj (junction the Retrofit LED Lamp Because LED lamps save energy and temperature) of an LED: drive current, The starting point for the analysis and extend the light’s lifetime, they are thermal system, and ambient design simulation is a set of functional likely to replace other technologies temperature. In general, the higher the relations for the thermal phenomena such as incandescent and fluorescent drive current, the greater is the and design parameter. The three lamps in signal solid state lighting, and generated heat, as shown in Figure 2. phenomena of heat transference are vehicle headlights. Many LED lamps Heat must be removed from the LED in conduction, radiation, and convection. are developed by light source order to maintain expected luminous The relation between the three industries, and the use of LED lamps efficacy and lifetime. phenomena and the design parameter has been increasing exponentially over are shown in Table 1. When the design the last few years. If it reaches the size Therefore, thermal management of the parameter is changed, each of GLS it will have spread remarkably LED is a crucial area of research and phenomenon changes accordingly. far all over the world. development.

Figure 1 (left): Light source history: luminous efficacy

Figure 2 (right): Relation of light source luminous efficacy and power

OLED LIGHTING AS SEEN IN TIME DESIGN SUMMIT MAGAZINE THE WORLD’S LEADING OLED LIGHTING EVENT

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OLED_LightDesign_EU11_A4_V1.indd 1 14/04/2011 11:32 THERMAL LED LAMP COOLING 50

Table 1: It means 4.51 W is dissipated as the Approach of thermal thermal loss on the LED chip, which, in management other words, is the heat source of the and thermal CFD model. The relation among Tj, Ta phenomena (ambient temperature: 25°C), Q

(thermal energy: 4.51 W) and Rt (total

thermal resistance between Tj and Ta) is shown in equation (EQ 1). Tj is 100°C, which is set with respect to the Conduction is the transmission of heat 75 lm/W luminous efficacy it is very LED chip quality assurance.

across a solid by way of kinetic energy important to control the Tj between atoms. Thermal flux within appropriately in order to avoid excess and between materials is proportional heat. In short, thermal management is to the temperature gradient and the the key approach to realizing the target cross-sectional area of the conductive specification. path. Before evaluating the characteristics of Convection is the transfer of heat by a lamp by means of a real prototype, it flow in a liquid or gas. Convection is very useful to use a modelling tool amount of thermal energy is for a feasibility study. Figure 3 shows proportional to the surface area and the CFD mesh model used in this the temperature gradient between the case. The LED chip is mounted on the surface and the fluid. substrate and the substrate is on the module plate. The module plate is Radiation is emitted energy by connected to the edge of the case. electromagnetic waves from the The electric circuit as an LED driver is surface of a solid. Radiation energy is included in the case. The LED chip Figure 3: Modelling the LED lamp proportional to the surface area and plays the role of the main heat source emissivity of the object’s surface. in the CFD model.

Therefore, it is necessary to design Based on this model, a thermal parameters according to thermal network structure is interpreted as phenomena for improving heat shown in Figure 4. By putting the dissipation. temperature result, which is calculated in the CFD model, into the thermal Consequently, analyzing the network, the values of thermal phenomena is very important for resistance are conducted. designing parameters. A comparison of each value would point out the branch which should be Design Concept of a improved for proper heat transfer. In Typical Retrofit LED Lamp Figure 3, the thermal energy from the Figure 4: Heat circuit of an LED lamp At the start of creating a design LED chip is mainly transferred to the concept, the desired targets of the substrate, the module plate, and the It Using equation (EQ 1) with the value

lamp specification should be clarified. case. Finally, it is discharged into the of Tj, Ta, and Q mentioned above, Rt

In this article, they are as follows: air from the surface of the case. First of was calculated, as Rt >= 16.63 K/W.

all one has to find the bottleneck This value Rt >= 16.63 is the boundary • Lumen output: >560 lm element of thermal transfer in this line for achieving the target • Input power: <7.6 W (i.e. lamp thermal network. The efficiency of specification of this lamp. Equation efficacy: >75 lm/W ) power conversion on the electric (EQ 2) shows the detailed structure of

• Weight : <100 g circuit is 86% in this case. Rt, Ra and Rb are the thermal resistance • Sophisticated lamp figure values of substrate and module plate

As a result, when 7.6 watts, as the each, Rair is the one of the gap

The lumen output mentioned above is input power specified, is loaded into between module plate and case, Rd is almost equivalent to a 40 watt the LED lamp, the 6.5 W that are the one of the region between the incandescent lamp. distributed would be consumed by the surface of the case and ambient. For LED chip. Then 68% of the distributed solving these equations (EQ 1, EQ 2),

The more the Tj is increased, the more power is converted to thermal energy Ra, Rb, Rair and Rd were derived by CFD the luminous efficacy of the LED chip (i.e 32% of it is emitted as light). model of a certain initial prototype is decreased. To achieve the target of design.

These values were estimated as

Ra: 2.08, Rb: 0.04, Rair: 2.75 and Rd: 16.0 K/W.

At this point, when considering thermal transfer mechanism on each of the thermal resistance

elements, Ra, Rb and Rair are mainly dependent upon material properties (i.e. thermal conductivity efficiency solutions of solid bulk). That is, unless it is adapted to change the material, it is generally difficult to by direct bond copper

change the thermal resistance, Ra, Rb and Rair.

On the other hand, Rd is dependent on not only the material properties of the case but also any

surface condition of it because Rd is defined on the boundary between solid and gas.

Furthermore, the ratio of Rd is the largest value among other ones in the equation (EQ 2), which

means that controlling the value of Rd would be

the most effective way to manage the value of Rt without changing the material of the case. Then,

suppose Ra, Rb and Rair to be fixed values as

mentioned above. Rd was calculated as 11.76 >=

Rd using the equation (EQ 3). Thus if Rd is less

than 11.76 K/W, the Tj can be kept below 100°C which is the maximum temperature allowed. The

critical value of Rd = 11.76 was determined as the target value here. What is needed is to decrease

Rd from 16.0 of the initial prototype case to 11.76 as the target value. designhouse

EQ 1

EQ 2 High thermal conductivity Excellent for chip EQ 3 on board Optimized heat spreading

As the second step, the thermal management DBC SUBSTRATE performance of the lamp case was the most

important element for controlling the value of Tj. Thermal resistance of the case, R , depends on d Highly integrated enveloped case volume [2]. The relation between cooler the enveloped case volume and thermal Outstanding thermal resistance is calculated as shown in Figure 5. performance When the enveloped case volume is 42,500 mm3, Customized design thermal resistance reaches 11.70 K/W. However, this volume (42,500 mm3) is not permitted DBC COOLER because this size is too big compared to the equivalent incandescent lamp which has been used up until now. Therefore, a different approach is needed for decreasing R as the third step. d curamik electronics GmbH Am Stadtwald 2 In fact, as shown in Figure 4, it is found that R d D-92676 Eschenbach A division of consists of two elements. These are: convective Phone +49 9645 9222 0 [email protected] elements (Rc) and radiative elements (Rr). Rc and www.curamik.com Rd are conducted from the equation (EQ 4 - EQ 6). The value of hc is the convection THERMAL LED LAMP COOLING 52

Figure 5: coefficient, which is similar to the heat transfer theory. h is Relation between r thermal resistance the radiation coefficients derived from Plank's law. Then, Rc and enveloping and Rr are calculated using these equations (EQ 4 - EQ 6). volume

2 Wherbey hc: convection coefficient [W/m K] | C: 0.55 |

The surface area (A) is set to 6,000 mm2 as a typical and desirable value. Emissivity of the case surface is 0.2 (pure aluminium). The results are shown in Figure 6. The weight of

Rr accounted for 83% of total thermal resistance. From these results, it was confirmed as the effective approach to improve the radiative performance of lamp case surface for Figure 6: finally decreasing R . The Thermal d resistance ratio of the thermal As stated above, the effect on decreasing Rd is estimated process when changing the lamp case surface characteristics. (in case of A: Figure 7 shows Rd dependence on the emissivity of the 6000 mm2 & ε: 0.2) lamp case surface. The emissivity is changed from 0.2 to 1.0. As the emissivity increases, Rd decreases. In addition,

Figure 7 also shows Tj which depends on the emissivity.

According to Figure 7, in case that Rd and Tj are made to satisfy the target value, i.e. R : 11.76 k/W and T: 100°C, it is Figure 7: d j found that emissivity should be more than 0.8. Then, Relation between thermal resistance authors adopted "anodizing on the surface" to increase the and emissivity emissivity from 0.2 to 0.8 and make an accurate prototype as the final step. As a result of temperature measurement on

this prototype, it is confirmed Tj reaches 98°C on the emmisivity 0.8, which means within 100°C.

Along with the mentioned steps, the very small size and more efficient retrofit LED lamp was successfully developed as shown in Figure 8.

Figure 8: LED product was Next Approach of Thermal Management designed with for LED Lamps proper thermal The investigation on a proper thermal management management structure for retrofit LED lamps, followed the four steps mentioned above based on the CFD model results.

This modelling will be also applicable for developing other LED products. LED products are likely to replace high- power lamps such as ceramic-metal-halide lamps in future. The more electric power is loaded to get high-brightness, EQ 4 the more the heat converted is increased.

Therefore thermal management will become more and more important for future LED products.

EQ 5

References: [1] Lighting Hand Book, pp. 102- 146 (2003) EQ 6 [2] Naoki Kunimine, Heat design complete introduction for electronics, pp.170 (1997) (in Japanese)

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210x144 landscape 3mm bleed.indd 1 21/04/2011 17:32 SPECIAL TOPICS LED ALERT DEVICE 54 HB-LED Alert Device with Intense Light Output

Jerry Vereen, Principal Engineer of Egret Technologies shows how LED technology opens fields for new applications and can make life easier. He gives insights in challenges and future perspectives.

The deaf community is using output, the cadence of the “flash” can Ring Strobe Signal standard Videophones and be controlled by the Videophone to When a call is received at the sign-language to communicate. allow different on and off times and Videophone it identifies the caller and Video Relay Services are also patterns based on received caller ID. drives a strobe signal to the Flasher. available to enable a deaf Similar to a caller ID on a phone, the The Flasher receives this signal and person to communicate with pattern of light pulses can be used to generates an intense flash of light to a hearing person by way of a identify the caller at a distance from alert the deaf person of an incoming sign-language interpreter at a the Videophone. The Videophone and call. The duty cycle of the Ring Strobe call center. This article discusses Flasher solution is shown in Figure 1. Signal determines the on time duration how Egret Technologies used and the off time duration according to LED technology in the design the caller ID pattern. of a product to provide an intense light output to alert the deaf person of an incoming Product Requirements Videophone call. The required size of the product needed to be about the size of a small PC speaker. The customer required Problem front, back, and side visibility of light. Standard off-the-shelf Videophones The design also needed to have a firm operate assuming the person can hear and sturdy feel and be heavy enough the ring signal and answer the call. so that attached cables would not pull However, calls are often missed for the the unit off a countertop or desktop. deaf or hard of hearing person. An The required unit cost also had to be attempt to solve this problem without very low (less than $20 (€14 EUR) to modifying the Videophone hardware the end user). was made by simply flashing the LCD screen of the Videophone on and off. The light intensity requirement was not Needless to say that the amount of directly specified, however, the light from the screen was just not Figure 1: Videophone and flasher customer required the need for a sufficient to call attention to a person in an adjacent room or with their back turned. Egret Technologies was given the task to provide a cost effective and innovative solution.

Solution The Alert Device (Flasher) provides a high output light “pulse” similar to a camera flash to call attention to the deaf person that a call is coming in. The Flasher is a separate device that sits near the Videophone and is attached to the Videophone. In addition to providing an intense light Figure 2: Videophone sends ring strobe to flasher

SPECIAL TOPICS LED ALERT DEVICE 56

strong flash similar to a camera flash, The initial demonstration at the Modules are then connected in series. but with the option to use longer on customer’s facility was done with a Read further to understand this design time durations. Customer approval single LED module. At that point the decision. was obtained before committing to customer requested that a second hardware, by Egret Technologies LED module be added. performing a live demonstration using Design Considerations an LED Driver Evaluation Kit, LED LED: Selection of the LED required Module, and sample lens at the Core Design Attributes obtaining samples and running some customer facility. The heart of the design consists of a tests in the lab. Based on these tests a Camera Flash Boost Converter IC and 3-LED High Brightness LED Module two High Brightness LED modules. was selected that has a wide The Light Source - Competing The Boost Converter is configured to dispersion angle of 120°. This provides Technology operate in strobe mode for this the desired distribution of light across Various lighting technologies were application. In this mode, the Boost the room. To approach 360 degrees of examined prior to the onset of the Converter switches continuously to light from the Flasher, two LED project. The primary contenders were supply maximum current for the LEDs, modules were used (one on each side the Xenon Flash Tubes and High but for a limited time. The current of the PCB). This approach allows the Brightness White LEDs. through the LEDs is regulated by the device to be placed almost anywhere Boost Converter and set by an external in the room, even against a wall. To Xenon Flash Tubes: resistor. The time duration of the strobe that end the PCB and Lens were • Flash “on” time limited to short signal (Strobe~) controls the LED on “arched” to extend the height of the bursts time. The Boost Converter consists of LEDs above the black plastic housing • Circuitry more complex a gated oscillator, a 24 V boost circuit, and provide side light. See Figure 4. • Very high voltages required to drive and an LED current-regulation circuit. the Xenon bulb complicating the UL The Boost Converter operates from a LED Configuration: The boost approval process 2.6 V to 5.5 V input range. For this converter’s 24 V output voltage is high • Higher part cost than LEDs application, the input supply was enough to drive a string of LEDs in • Higher manufacturing assembly sourced from a wall-mounted AC/DC series. For this design a combination costs due to package type power supply that outputs +5 VDC of series and parallel is used. • Shorter bulb life at 1A. Note that parallel LEDs may exhibit High Brightness LEDs: With two LED modules there is enough slight variation in forward current from • Supports longer “on” times light output to alert the person, even if LED to LED resulting in differences in • Operates from “safe” low voltages they are not close to the Flasher. Each brightness. This affect is minimal if the • Surface mount package can be LED module has three LEDs which are LEDs are on the same substrate as is placed by machine reducing connected in parallel in the design. The the case for this application. manufacturing assembly and labor cost • Lower part cost • Longer life • Off-the-shelf LED driver chips available

Figure 3: Typical Xenon flash tube (left) and CREE CLP6B- WKW-CD0E0453 LED package (right)

Although the xenon flash tube does provide an intense and pure white light output, the LED solution was better especially in terms of lower design complexity and lower cost. Finally, the ability to have longer on times was a plus.

Figure 4: LED module location

Given the 24 V output of the Boost Converter and the worst case

VF = 4.4 V of an individual LED, the following scenarios fall out:

6 LEDs in series: 6 × 4.4 V = 26.4 V (voltage drop too high for Boost Converter)

2 LEDs in series, 3 in parallel: 2 × 4.4 V = 8.8 V

The 2nd scenario is a reasonable compromise between a series and parallel configuration and was the one Egret Technologies chose for this design. The LED Modules are then Figure 5: Flasher circuit block diagram placed in series to ensure that both Modules are driven at the same current level, while the individual LEDs providing a clean feedback signal with the external LEDs are off. Conversely, within each Module are in parallel. See little noise, as is true with any switching when the enable pin is high the LED Figure 5. regulator design. The Boost Converter driver turns on and the LEDs illuminate. controls LED brightness by regulating Figure 6 depicts the 24 V precharge LED Brightness: LED Brightness is the current through the LEDs to a state (LEDs off) and the LED on state determined by forward current. The selectable level controlled by an where ~7.6 V is dropped across the LED Module is specified for a external resistor. The current into the output (due to 2 series LED’s). continuous forward current of each LEDs is regulated to 1000 times the LED in the Module at 50 mA. This was current set by the STB pin resistor, Schmitt Trigger Buffer: The Strobe

the current level that was chosen and RSTB. When the EN pin is low the signal from the Videophone was configured to be driven by the Boost converter is in precharge mode and treated with additional care as the Converter. Maximum peak forward the converter switches continuously signal is being driven over a cable LED current is 100 mA for each LED, until the output capacitor is charged to several feet. Being a TTL level signal allowing for an additional 50 mA of 24 V. Once the OUT feedback pin and the fact that capacitance in the current margin. Maintaining LED reaches 24 V, the converter does not cable would slow the edges, an input current control was critical to the switch again until OUT falls below buffer was added to the design to design and this was handled by the 23.5 V. This results in 500 mV ripple on clean up the signal, rather than Boost Converter as follows. the output. The LED pin is high connecting directly to the Boost impedance in the precharge state and Converter’s enable pin. The buffer The typical forward drop of an individual LED is 3.8 V at 50 mA. The strobe current is then set by the

resistor RSTB. From the Boost Converter’s data sheet,

RSTB = 600 / ILED. Since there are 3 LEDs in parallel the current is evenly divided for this estimate.

ILED = 3 × 50 mA = 150 mA,

therefore desired ILED = 150 mA

Now calculating RSTB:

RSTB = 600 / 150 mA = 4 kΩ

Boost Converter: The Boost Converter is actually a switching regulator designed to drive LEDs, therefore careful attention to the selection of inductor, input capacitor, and output capacitor is prudent, as well as in Figure 6: Scope plot of boost converter’s LED drive

selected has a schmitt trigger Cadence Ideas for Caller ID input stage which adds hysteresis Caller ID can be used to provide to the switching region. The buffer unique per caller (or per caller also protects the boost regulator group) flash sequences, from external voltage transients controlled by the pulse width and that might otherwise damage the timing of the strobe control signal. boost regulator. Finally, a pull-up resistor was added to the input of The following methods illustrate the buffer to ensure that the the concept: enable signal is deactivated when there is no cable connected from • Combine a number of the answering device to the successive high brightness Flasher, while power is applied to flashes with different off times the Flasher. between groups of flashes • ON, Long OFF, ON, Long Mechanics: The enclosure is a OFF, etc molded plastic housing (ABS • ON, short OFF, ON, Long Figure 7: Mechanical design UL94-V0) customized for OFF, etc appearance and application. The • ON, short OFF, ON, short Lens is polycarbonate UL94-V0 OFF, ON, Long OFF, etc and tinted white with 50% • Combine “low” level LED translucency. A weight is placed flashes with high level LED inside the bottom of the unit to flashes, e.g. A 400 provide stability. microsecond LED On pulse is still visible and these low light “blips” could be interspersed Application Hints with high brightness flashes to LED On Time: There was no convey ID information. The limitation built into the Flasher Long Off time could contain a hardware design to prevent number of these low light excessively long LED on times. At pulses. the same time, however, the brightness of the LEDs was critical to user satisfaction. Since Conclusions current is pulsed to the LED, the Applications for High Brightness highest brightness is obtained by LEDs are evolving into many providing a short duration flash. If areas and uses. To ensure that the LED is left on for a “long” the LEDs truly provide years of time, the power consumption is operation in an application, the high and the parts can build up electronics that drive the LEDs heat. Although no damage can must be designed carefully and occur due to this scenario, it was with plenty of margin built in. The recommended to use LED On approach that Egret Technologies times shorter than 200 ms. took was to design from a systems perspective. After all, it LED On Time Specification does not matter what fails, the life (High Brightness Flash). of the LED is dependent on the Condition: life of the supporting electronics New ILD 4001 step-down LED controller – perfect Strobe control line from the as well. fit for various lamps and general lighting systems Videophone in the low state, LED On Time Spec: This brand new product offers you maximum design 30 ms (typical), 200 ms flexibility. (maximum)

Scalable output stage with external MOSFET up to 5A Choice of dimming concepts – PWM or analog voltage • “On” times shorter than 30 ms Supply voltage for 12V, 24V and 40V applications can be used to convey caller ID Overcurrent, overvoltage and thermal protection info • “On” times in the 30 ms to To learn more about the LED driver portfolio for General Lighting, please visit 100ms range provide a high [ www.infineon.com/lowcostleddrivers ] brightness output

LED_Professional_98x88_ANZ.indd 1 19.04.2011 16:41:05

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CR3453 LEDProf 05-06/11 LED Revs Mark MT-G AF.indd 1 4/9/11 4:30 PM