July/August 2018

Special Report: Automotive Electronics + Infotainment (pg 25) crystal clear POWER SYSTEMS DESIGN JULY/AUGUST 2018 frequencies.

2 2013 VIEWpoint Power design One Giant Leap for the Power Industry Technology-Driven Optimization for By Ally Winning, European Editor, PSD Power and Thermal Tradeoffs By Frank Schirrmeister, 4 MARKETwatch Cadence Design Systems Automotive Infotainment Developments COVER STORY By Kevin Parmenter, Field Applications Optimizing Class-D Audio Amplifier Engineering, Advanced Energy SPECIAL REPORT: AUTOMOTIVE ELECTRONICS Output Filters (pg 9) 6 DESIGNtips + INFOTAINMENT

Optimizing Thermal-Mgmt for 26 Automotive Infotainment System Performance and Reliability By Rudy Ramos, Mouser Electronics Designs Get Easier By Steve Knoth, Analog Devices, Inc.

31 © eiSos Transient Protection Solutions in COVER STORY Automobiles 139 Optimizing Class-D Audio By Ron Demcko, Fellow, AVX Corporation Highlighted Products News, Industry News and #CRYSTALCLEAR Amplifier Output Filters more web-only content, to: 37 Wide Bandgap SiC Devices for By Christopher Hare, Technical www.powersystemsdesign.com Marketing Engineer, Coilcraft, Inc. Auto Power Electronics By Dennis Meyer, Applications Engineer, 44 FINALthought and Jason Chiang, Strategic Marketing Is Form Over Function a Choice TECHNICAL FEATURES Manager, Microsemi for Computers? 40 By Ally Winning, European Editor, PSD Microcontrollers Evolve to Support 12 Test & Measurement electronica Hall B6 Booth 404 BLDC Automotive Needs 44 Dilbert The WE-CMBNC is a VDE certifi ed series of common mode chokes with a highly permeable Simplifying Complex Measurements with a Source By Spencer Manley, and Mathias Müller, nanocrystalline core material. Despite the small size, it delivers outstanding broadband  High permeability nanocrystalline core material By Tom Ohlsen, Tektronix Rutronik attenuation performance, high rated currents and low DC resistance values. Low profi le and high  High IR & low RDC in a small size voltage ratings can also be realized by the common mode chokes of the WE-CMB family.  Broadband suppression 17 Battery Technology  Stable inductance values at high For further information, please visit: temperatures Battery Technology: Power to the People By Mark Patrick, Mouser Electronics www.we-online.com/we-cmb  Improved isolation through plastic case and patented winding spacer

Nanocrystalline MnZn NiZn MnZn/NiZn Horizontal High Voltage WE-CMBNC WE-CMB WE-CMB NiZn WE-ExB WE-CMBH WE-CMB HV WWW.POWERSYSTEMSDESIGN.COM 1 VIEWpoint POWER SYSTEMS DESIGN

One Giant Leap for Sound Choice

Power Systems Corporation 146 Charles Street the Power Industry Annapolis, MD 21401 USA Tel: +410.295.0177 Fax: +510.217.3608 www.powersystemsdesign.com

Editorial Director Welcome to the July/August edition of Power Systems Design. Traditionally things quieten Jim Graham down a bit over the summer period and we get a chance to take some well deserved rest and [email protected] relaxation. This year that rest is even more welcome as things seemed to increase in intensity as the year went on. Editor - Europe Ally Winning Things came to a head at PCIM in Nuremberg in June. This year’s show had groundbreaking [email protected] innovation across the industry. To try sum it up in a couple of sentences is difficult, but I think Editor - North America it is safe to say that this year wide-bandgap materials truly came of age. It would possibly be Jason Lomberg more accurate to highlight GaN technology, which was everywhere at Nuremberg. To sum up [email protected] the show, one senior executive told the press that if we were ever going to write a book, now was the time and GaN should be the subject, because future power engineers will look back Editor - China at the today in the same sort of way that computer engineers look back at the PC revolution Liu Hong led by IBM and Microsoft in the 1970s and 1980s. [email protected] That may be a bit hyperbolic, but there was a sense of history being made at the show. GaN Contributing Editors Kevin Parmenter, PSD technology is set to penetrate all areas of the industry that use 800V or lower supply voltage. [email protected] Above that figure, SiC is also making a similar impression, particularly in the automotive industry. SiC has the potential to make the conversion and distribution of power in electrical Publishing Director vehicles much more efficient and the components lighter, which in practical terms means Julia Stocks longer driving times and quicker recharging. If we could find a better method of storing [email protected] power to combine with SiC technology, almost all of the drawbacks of electric vehicles would disappear. Creative Director Chris Corneal The automotive industry is also the subject of our special report this month. While SiC [email protected] will play a major part in the industry, it is not the only concern for power engineers in Circulation Management the automotive sector. In electrical vehicles, hybrids, and even fossil fuel driven vehicles, Coilcraft dual inductors for Class-D output fi lters Sarah Corneal consumers are demanding the latest technologies, whether that be for infotainment, HUDs [email protected] or many other innovative technologies. These technologies usually depend on highly complex provide low distortion and the best possible sound quality processors with demanding power needs. Designers of consumer equipment have solved Sales Team these problems, but it is more difficult for designers of automotive equipment, who need to Marcus Plantenberg, DACH-Region take extreme temperature variations and electrical noise into consideration. This month we [email protected] have two articles that take different approaches to powering complex automotive applications. The first from Analog Devices looks at making the power management ICs used by consumer Based on their high power effi ciency, small ultra-low total losses minimize the impact on Ruben Gomez, North America [email protected] equipment more rugged, and the second from Cadence looks at solving the problem much size, and light weight, Class-D amplifi ers are total harmonic distortion plus noise (THD+N), earlier in the process. Both methods have pros and cons, what will suit your application best? Registration of copyright: January 2004 a popular choice for extending battery life in greatly improving audio quality. ISSN number: 1613-6365 DC-powered audio applications, such as those And housing dual inductors in a single Best Regards, Power Systems Corporation and Power Systems found in automotive sound systems. shielded package saves critical board space. Design Magazine assume and hereby disclaim any liability to any person for any loss or damage Ally Winning Coilcraft offers a unique selection of dual Learn more about our economical solu- by errors or ommissions in the material European Editor, PSD contained herein regardless of whether such [email protected] inductors that signifi cantly improve the per- tions for a wide variety of audio amplifi er errors result from negligence, accident or any other cause whatsoever. formance of Class-D output LC fi lters. Good applications. Free Magazine Subscriptions, go to: linearity of the inductance with current and Visit coilcraft.com/Class-D today! www.powersystemsdesign.com

® Volume 15, Issue 6

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Automotive Infotainment Optimizing Thermal-Mgmt for Developments Performance and Reliability By: Rudy Ramos, Mouser Electronics By: Kevin Parmenter, Field Applications Engineering, Advanced Energy ower conversion is ambient-temperature range. when delivering the required few of my favorite the automotive and infotainment server farms. Information will be common to almost all The small proportion of power power to the load, the design programs include customer experience. In fact IHS fed into the vehicles via wireless electronic systems. that enters the power transistors effort must focus on reducing “Weaponology,” projects 1500 dollars of electronic including 5G from cellular base Efficiency is critical, but is not transferred to the θja. A variety of techniques can “Future Weapons,” content per vehicle or more within stations, as well as via wireless Pwhether the objective is to load is dissipated from the be used to achieve this. These A“Modern Marvels” and the a few years. Bluetooth, Wi-Fi and DSRC maximize runtime for a small junction of each device. The include: science show “Connections.” communications. Vehicles will battery-powered device, reduce junction temperature is related • Package selection, taking They all explore the various paths The Society of Automotive more and more include charging utility costs to power data- to this power dissipation by the advantage of packages with of technological change and Engineers defines five levels of – wireless and otherwise – for center servers, or others such equation: enhanced internal features interrelations and the significant vehicle automation. From Level 0 consumer electronics, including as ensuring cost parity for like thermally efficient clips effects that this change has on essentially means no automation built in inverters to take our AC renewables. Tjmax = (PDmax x Rθja) + Ta to replace conventional society, including that in order to level 5 full automation, no line powered systems on the road wirebonds, or enlarged for one thing to be developed, driver needed but may take over if if needed. Efficiency is never 100%, even Where Tjmax = maximum metallized areas on the enabled and built upon, prior required. Full automation allows in the best systems. That small junction temperature lower or upper side of the developments had to be invented us to enjoy the infotainment Since we’ll be spending less time amount of un-transferred energy PDmax = maximum power die - or both sides for dual- and built upon. system that much more! driving and more time riding, is converted to heat, which then dissipated side cooling; these areas are we’ll have the ability to enjoy presents reliability challenges. Rθja = thermal impedance from connected directly to a heat This is certainly the case with the For us to not only climb the our commute times a bit more Without effective thermal junction to ambient slug or exposed metal pad automotive and infotainment automation hill to get to Level 5 than we do now, and can even management, heat-dissipating Ta = ambient temperature that can be soldered to PCB industry. The rapid developments we must continue to advance in be more productive. Incidents of components like power metallization or attached to a occurring in the automotive all areas, including Night Vision – accidents should also decrease transistors or resistors can When designing a power supply, heatsink. electronics arena can trace their Lidar – radar and sensing systems, as safety systems and software run too hot – leading to early the objective is to design for a • Board design, including origins back to electric motors vehicle-to-vehicle communications get better, increasing occupant failure - or in extreme cases may junction temperature that will increasing the copper and electrical developments, time systems, electrification of the safety and reducing insurance exceed their maximum rated not only preserve the device thickness, or adding thermal delay wipers, and radios in cars; drive train and power electronics, rates. Biometrics and tracking temperature resulting in rapid but also ensure the desired vias directly beneath the hot however, propelling forward the graphics – computing and systems will reduce – possibly destruction. reliability. The maximum power components connecting to developments in other segments AI. Video and ultrasound even eliminate – vehicle theft . dissipation can be estimated a heat spreader such as a (consumer, communications, imaging systems, driver-vehicle While the speed of this evolution Reliability follows the Arrhenius using the datasheet efficiency heavily metallized layer. An wireless and cellular, gaming, communication systems and is unknown, we do know we are Law, which incentivizes cooling: curves. Similarly, the thermal insulated metal substrate embedded control and computing) interfaces – voice and data, and building on technology developed reducing a component’s impedance, θja, from junction may also be considered connectivity, power electronics, of course the rapid development from days to decades ago to operating temperature by to ambient, can be found from if extremely high heat LED lighting, Military technology, and continued development of create a future of automotive and 10°C can double its lifetime. datasheet curves that also dissipation is needed. Radar Wi-Fi, Satellites, GUIs and memory technologies. Vehicles infotainment systems that will Moreover, taking steps to ensure consider cooling effects such as • More overt thermal- software, class D audio and AV are generating lots of data and will benefit us all. a lower junction temperature PCB metallization and airflow. management techniques, systems, motor drives, battery do more so in the future. The data can increase power capability such as heatsinks or heat technologies and more are coming must be stored and processed PSD and allow the power supply to If an acceptable junction pipes, possibly in conjunction together to drive the future of not only in the vehicle but also in www.powersystemsdesign.com operate safely across a wider temperature cannot be achieved, with a cooling fan.

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The question arises as aluminum, or copper, they can to which combination range from simple stamped of these techniques metal wings intended to be should be used for applied to a single transistor, optimum effectiveness, to milled or extruded parts with acceptable size and finning designed to intercept weight, and minimal convection airflow for maximum impact on Bill Of heat transfer. Convection occurs Materials (BOM) naturally, as warmed air rises, cost. The answer is which perpetuates the flow. not always obvious, Care must be taken to ensure but the potential unimpeded airflow from inlet to consequences of over- outlet, also making sure the inlet or under-engineering is placed below the level of the the solution are clear. Figure 2: Heat pipes are available in various shapes and sizes, or can be heatsink and the outlet above. Building multiple customized, to transfer heat to a convenient place to be dissipated by a This is necessary to prevent prototypes to explore heatsink fan. heated air stagnating above different thermal or heat pipe to remove thermal Adding a Heatsink the hot component, which can designs may not be energy from the system more A heatsink is easy to understand exacerbate junction-temperature viable. On the other Figure 1: Adding a heatsink to boost top-side cooling of thermally enhanced power package. quickly. The temperature plot and extremely reliable, with no rise. hand, if the chosen solution the chosen controller or DC/ To run a simulation, the user can help focus attention on the moving parts, no failure mode, is found to be unsuitable later DC converter IC and known enters settings like the load areas of main concern. and no operating cost. Usually Despite their many advantages, in the project, redesigning the requirements like power-supply current, top and bottom ambient board to add extra thermal vias input and output voltage ranges. temperature, and device or to accept a different package case temperature. A thermal style may be impractical. Once the basic design is simulation can be run in a few completed, WEBENCH compiles minutes, capturing results that Fortunately, help is at hand. the bill of materials and can be analyzed graphically Thermal simulation software calculates parameters such using the color temperature can help engineers visualize as power dissipation and θja. plot. If necessary, the design can thermal behavior from a These can be used to calculate be changed within WEBENCH system perspective and identify Tjmax manually, using known to optimize the thermal any problem areas before ambient-temperature data. performance, by changing committing to a first prototype. However, running a webTHERM the board size or copper simulation allows users to characteristics on any of the Some online tools are even see the thermal performance layers, or adding and adjusting available free of charge. TI’s graphically, and also shows thermal vias. WebTHERM™ is an example, secondary effects such as co- which is ready to perform heating of components that Multiple simulations can be EXCEED YOUR LIMITS! thermal analysis on a power can be difficult to visualize run and compared to identify supply design created using otherwise. The result of a design that produces an the WEBENCH® online the simulation is a color acceptable temperature. If HIGHEND QUALITY ELECTRONIC COMPONENTS environment. The power temperature plot that helps a suitable Tjmax cannot be supply is initially designed as quickly identify any areas of assured, additional thermal a WEBENCH project, using concern. management such as a heatsink

Telecommunication, Information, Consumer, 6 WWW.POWERSYSTEMSDESIGN.COM Industry and Automotive Electronics www.taiyo-yuden.com DESIGNtips COVER STORY

heatsinks can become large, can be transferred from the heat pipe in the most suitable heavy and costly if sized to base of the heatsink to the location. dissipate large quantities ambient environment. Optimizing Class-D of heat. The constraints on Forced-Air Cooling positioning for best airflow Extend Design Freedom with If passive thermal management Audio Amplifier Output Filters may compromise board layout, a Heat Pipe using heatsinks or heat pipes and fins can become clogged In some designs, constraints is unable to achieve the desired Careful component selection is the key to high-quality high-efficiency with dust or dirt and so impede on overall size or board layout, junction temperature, forced- cooling. Attaching the heatsink or impeded airflow, may air cooling using a high-quality Class-D audio output properly to the component, with prevent attaching a heatsink of fan from a manufacturer such clips or screws and a layer of the required size directly to a as Delta Electronics may be By: Christopher Hare, Technical Marketing Engineer, Coilcraft, Inc. thermal interface material (TIM), converter IC or power transistor. considered. A fan gives the hen audio able temperature. This wastes practice due to the uncompro- also adds to assembly time. A heat pipe (Figure 2) can offer flexibility to optimize cooling by applications re- energy and adds weight to the mising second law of thermody- a practical alternative, which selecting fan size and adjusting quire the highest overall design. Class B amplifi- namics, the efficiency of Class-D A vast variety of heatsinks are enables heat to be moved from speed to increase or decrease power efficiency, ers dissipate less power, but have amplifiers is significantly higher available from manufacturers the source to another location the airflow, rated in cubic feet Wlowest heat generation, smallest inferior sound quality due to non- than the linear amplifier classes, such as Aavid Thermalloy or where a suitable heatsink or per meter (CFM). size, and lightest weight, Class-D linear crossover distortion of the achieving over 90% at full load. Wakefield-Vette, including parts spreader can be positioned, switched-mode amplifiers sur- push-pull controller transitioning With proper design, sound qual- that are optimized to fit specific and greater airflow provided for Conclusion pass the linear class amplifiers. between on and off conditions. ity can be comparable to Class- components, such as processors cooling. The part illustrated, the Proper thermal management is This makes Class-D amplifiers AB. or FPGAs. On the other hand, Wakefield-Vette model 120231, essential to maximize both the the best choice for extending Class-AB is a compromise be- heatsink selection can be based can handle thermal loads up to performance and reliability of battery life in DC-powered au- tween Class-A and -B characteris- Basic Operation of Class-D on calculations that consider 25W but is only 6mm diameter board-mounted power supplies dio applications, such as found tics. It has less dissipation than Now that we have chosen Class- its effect on reducing θja, the × 100mm long. or DC/DC converters. in automotive sound systems. Class-A, eliminating crossover D for our audio amplifier design, overall thermal impedance Designers have plenty of This article discusses how care- distortion and giving good sound let’s outline the operation of from the chip junction to the The heat pipe does not act as tools at their disposal, but ful design of the output LC filter quality. However, Class-AB still Class-D amplifiers. The basic air surrounding the heatsink, a heatsink itself but is a sealed it is essential to avoid over- stage of a Class-D amplifier leads has significant dissipation and Class-D block diagram is shown resulting in lower junction tube designed to transfer heat engineering to prevent to high efficiency and high sound an upper theoretical limit on in Figure 2. In the first stage, the temperature relative to power from its hot end to the cool excessive bulk, BOM cost, or quality, and how choosing the efficiency lower than the Class-B low-voltage audio input is com- dissipation. end by leveraging phase-change complex assembly challenges. right inductor affects these criti- limit of 78%. This can be a ma- pared to a triangular waveform principles. Heat is absorbed at Accurate thermal simulation cal parameters. jor disadvantage for DC-powered to generate a train of fixed-am- Figure 1 shows a power the hot end and vaporizes the tools are available free of audio systems, especially at high plitude square pulses. Next, the transistor in a thermally working fluid inside the tube. charge, which provide a visual Efficiency and Sound Quality power levels. pulse-width-modulated (PWM) enhanced packaged designed for The vapor travels towards the guide to thermal-management Considerations pulses are fed to the switch- efficient dual-sided cooling using cool end and condenses back challenges before committing Linear amplifiers have very low The theoretical efficiency limit ing controller and output stage, a top-mounted heatsink and a into liquid releasing its heat to building hardware. Other theoretical limits on power ef- of Class-D amplifiers is 100%. which functions similarly to a heat spreader in the PCB. The in the process. The liquid then techniques such as a custom- ficiency. While distortion for While this cannot be achieved in backward synchronous buck con- system is shown modeled as a travels back to the hot end of selected heatsink, heat pipe, Class-A amplifiers is low, the network of thermal impedances, the pipe to repeat the sequence. or cooling fan can help ideal upper limit for Class-A Rth, between the active junction Among the advantages of a overcome broader system efficiency is only 50%. The high and the ambient environment heat pipe is that no power is constraints on circuit layout or resistance of the output stage above and below the board. required to sustain this phase- airflow. transistors results in dissipation The thermal impedance of change mechanism, and the that generates significant heat, the heatsink, Rth heatsink, designer has the freedom to Mouser Electronics typically requiring large heatsinks expresses how efficiently heat position the cool end of the www.mouser.com to keep the design at an accept- Figure 1: Comparison of Amplifier Class Attributes

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needed for linear- each audio ity and channel. minimizing Keeping distortion the compo- and noise. nent count Higher to a mini- current re- mum helps quirements reduce typically the total necessitate Figure 2: Class-D Amplifier Diagram Source: https://en.wikipedia.org/wiki/Class-D_amplifier required real a larger verter. The most common con- Low-pass LC Filter Design estate. Figure 3: Class-D Type-1 Differential Bridge Tied Figure 4: Class-D Type-1 Single-Ended Equivalent inductor figuration for the output stage is For very cost-sensitive or smaller Load (BTL) Circuit Circuit size to bridge-tied load (BTL) which has form factor requirements, filter- The typical Class-D LC filter im- LBTL = Series inductance quency over the expected range minimize distortion. Having 2x more voltage swing across the less solutions may be feasible, plementation is a second-order CBTL = Differential bridge tied of speaker impedance, typically two uncoupled inductors in a load compared to single-ended but these can lead to EMI prob- Butterworth LC filter, which cre- load capacitor in the 2-8 Ohm range, allows the single package minimizes the and 4x the output power. The re- lems and high-frequency power ates a flat pass-band and phase RBTL = Differential (speaker) designer to determine whether LC filter footprint, saving criti- sult is a higher-frequency, higher- dissipation due to the switching response with a small number load the performance is acceptable cal board space in space-con- voltage square wave being fed to waveforms. A filterless design is of components. A second order RL = Single-ended equivalent for that range. strained applications such the load, typically a 4 Ohm or 8 not practical in a “noisy” auto- filter gives -40 dB per decade. load = RBTL / 2 as automotive Class-D audio Ohm speaker. motive environment. As with Selection of the LC values re- C = Single-ended capacitor tied Consult the LC Filter Design ref- systems. all things engineering, there are quires an understanding of the to ground = 2 x CBTL erence below for a more detailed Before the square wave is fed to trade-offs in performance vs. size speaker load impedance varia- The L and C values for a criti- discussion of the Type-2 and hy- The objective measurement the speaker, it must pass through and cost of the LC filter com- tion for the application. The cally damped Butterworth filter brid filter implementations and that defines sound quality is a low-pass LC filter in order to re- ponents. Using proven Class-D ideal L and C values result in a are: capacitor selection. For Type-2, total harmonic distortion and move the high-frequency switch- reference designs and evaluation critically-damped response with the only difference for the sin- noise (THD + N). Low THD + ing content and pass only the modules as a starting point can a flat passband and flat phase gle-ended analysis is that Cg = C N is crucial in the typical hea- audio frequency range (typically help reduce the time needed to response. An overdamped compared to CBTL = C/2 for Type ring-sensitive 1 kHz to 6 kHz 20 Hz to 20 kHz) to the speaker. design and test an optimal solu- response attenuates the audio 1. For the hybrid type, adding frequency range. The optimal in- The LC filter also limits the resid- tion, however, there certainly are content, and an underdamped where ω0 is 2 x π x f0 caps Cg to ground (Cg ~ 1/10th ductor choice involves trade-offs ual ripple current at idle condi- interesting challenges in design- response leads to peaks that of CBTL) improves the filtering in peak current handling, core tions, which improves efficiency. ing Class-D LC filters. Under- may trigger built-in circuit pro- For a cutoff frequency (f0) of 40 by coupling high frequencies to and winding losses at operating The switching frequency of the standing the requirements can tection or harsh sound. kHz and a 4 Ohm speaker load: ground. conditions, and part size. Class-D amplifier determines the provide insights into any trade- Inductor manufacturers, such filter order and cutoff frequency offs that may need to be made. Class-D BTL filters are defined C = 1.4 uF and CBTL = C/2 = 0.70 Inductor Selection as Coilcraft have designed requirements. Higher switch- by three types: Type-1, Type-2, or uF For the 4 Ohm to 8 Ohm speak- single and dual off-the shelf ing frequencies allow for smaller The output LC filter is a critical hybrid. The type defines a differ- The nearest standard capaci- er range, typical LBTL values inductors specifically tailored for components and lower order element in determining the size, ential (Type-1), common mode tance value is 0.68 uF range from about 5 to 20 uH, Class-D audio applications. filters to achieve the required sound quality, and efficiency of a (Type-2), or hybrid filter imple- and Coilcraft offers a selection These inductors balance the attenuation in the stop band, but Class-D sound system. The out- mentation that depends on the L = 11.25 uH. of off-the-shelf inductors in this requirements for both high- this may cause higher EMI and put filter is designed to attenu- pulse width modulation (PWM) The nearest standard inductor range for Class-D applications quality sound and high switching losses. In most Class- ate the high frequency switching scheme (AD or BD). Type-1 fil- value is 10 uH. for various power requirements. efficiency. D audio applications, the switch- component while passing the ters with traditional AD modula- Selecting an inductor that does ing frequency is in the range of audio frequency band of 20 Hz to tion are the simplest and will be Once the L and C values are se- not vary significantly with cur- Coilcraft 200 kHz to 2 MHz. 20 kHz. One low-pass LC filter is used in the following example. lected, graphing the gain vs fre- rent is important in maintaining www.coilcraft.com

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the input current. Simplifying Complex SMU CH2 is configured Measurements with a Source as an electronic Here’s how two-channel SMUs can speed up DC-DC converter and load by setting it to FET testing sink current By: Tom Ohlsen, Tektronix (source a negative n today’s fast paced world of Figure 2: This is a typical load regulation test setup using two SMU channels. current). In electronics design, complexity required the use of a couple of regulation and line regulation this mode, the SMU instrument represents evil and must digital multimeters, a power because they're among the most will operate in the fourth quadrant be avoided at all cost while supply, and an electronic load. commonly performed tests. and sink current. Isimplicity represents all that is However, the DC characterization right and good. Ok, maybe it’s not can be simplified by replacing all of Load Regulation The SMU channels are configured quite that extreme, but when it these electronic instruments with Load regulation refers to a DC- using the remote sense, or four- comes to test and measurement, Figure 1: The use of one SMU channel on the input terminal and another on a single two-channel SMU. SMUs DC converter's ability to maintain wire, connection. Using a four-wire simplicity is the engineer’s best the output terminal replaces several instruments. are well-suited for testing a wide the specified output voltage as the connection eliminates the lead friend because it saves time and followed by techniques for • Input and output voltage variety of I-V parameters of DC- load current (ILOAD) varies under resistance that would otherwise effort and yields more consistent simplifying FET device testing accuracy DC converters because they can a constant VIN. Typically, the load- affect measurement accuracy. and accurate measurement results. with an SMU. As these examples • Quiescent current source and measure both current regulation test is performed over With the four-wire method, the illustrate, working with an SMU • Efficiency and voltage, as well as function the entire range of load currents. source outputs using one pair of One instrument that maximizes takes fewer step and delivers • Turn-on time as an electronic load. Note that to test leads (between Output HI and simplicity for many common critical measurement insight. • Ripple complete the full range of DC-DC Figure 2 shows a typical load Output LO), and the voltage drop measurements is the source • Transient response converter tests, an oscilloscope is regulation test setup using two is measured across a second set of measurement unit (SMU), which Simplifying DC-DC converter required with the SMU providing SMU channels. SMU CH1 supplies leads (across Sense HI and Sense combines a power supply, a digital characterization Typically, electrical characterization input voltage and the load current. the input voltage and monitors LO). Connect the sense leads as multimeter, current source and Like any device, DC-DC converters of DC-DC converters involves electronic load in a single box. need to be characterized by sourcing and measuring input Using one instrument rather than This results in a test instrument manufacturers and by engineers voltage (VIN), measuring input multiple units simplifies the test that is more versatile than the evaluating them for a design. current (IIN), measuring the implementation, software, and individual instruments are alone, Given the increased pressure to output voltage (VOUT), and synchronization, as well as taking simplifies test setups and reduces develop products that consume sinking a load current (IOUT). up less rack or bench space. As measurement steps as well as the less power, design engineers are From these measurements, the shown in Figure 1, using one potential for error. looking for ways to increase power efficiency and other parameters SMU channel (CH1) on the input conversion efficiencies. Numerous can be determined. The efficiency terminal and another SMU channel Rather than spend a lot of time measurements are required is important for most designs, (CH2) on the output terminal of trying to explain how an SMU to characterize the electrical especially battery-powered the DC-DC converter replaces simplifies measurements, it might parameters of DC-DC converters. products, because it directly affects several instruments. be easier to show by example. Tests include: the running time of the device. To that end, here we first look at DC-DC converter characterization how to simplify DC-DC converter • Line regulation Traditionally, the DC involves testing many electrical characterization with an SMU • Load regulation characterization of these devices parameters. We'll focus on load Figure 3: Here is the result for a typical load regulation test.

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in its intended applications. is connected measurements. After connecting These I-V tests may include gate to the gate of the instrument to any computer leakage, breakdown voltage, the MOSFET with an Ethernet cable, entering threshold voltage, transfer and the Force the IP address of the SMU into characteristics, drain current, HI terminal of the URL line of any web browser on-resistance, etc. FET testing SMU CH2 is will open the instrument’s often involves programming connected to web page. From that page, the and synchronizing several the drain. The user can launch the embedded instruments, including a sensitive source terminal software and configure the ammeter and multiple voltage of the MOSFET desired test or tests, which can sources, which can be tedious Figure 5: This is a DC I-V test configuration for a is connected to often be saved and recalled for and time consuming. Although MOSFET using a two-channel SMU. the Force LO future use. a turnkey semiconductor characterization system solves the integration problem, systems of this type typically cost tens Figure 4: This shows the result for a typical line regulation test. of thousands of dollars. A third close to the device as possible, both SMU channels are connected approach involves using SMUs. which will minimize lead resistance to the DC-DC converter in the The number of SMUs required from adding to the measurement. same way they were for the load in the test usually depends on regulation test. the number of FET terminals Figure 3 shows the results of a that must be biased and/or typical load regulation test in However, for this test, the measured. which the DUT was configured to input voltage is swept over the output a constant 3.6V. SMU CH1 specified input voltage range and An FET is a majority charge- was set to bias 5 V (nominal value) the output voltage is measured. carrier device in which the to the voltage input terminal. SMU The load current is typically set current-carrying capability is CH2 was configured to sweep a to 0 A. Figure 4 shows the result varied by an applied electric load current from 0 to 1 A and from a typical line regulation field. It has three main terminals: measure the resulting output test. One channel of the SMU the gate, the drain, and the voltage. Measurements were taken instrument (SMU CH1) was source. A voltage applied to under software control. The load configured to sweep voltage on the gate terminal (VG) controls regulation percentage can be easily the input terminal of the device the current that flows from the calculated from the I-V data. while the other (SMU CH2) source (IS) to the drain (ID) Figure 6: This MOSFET drain family of curves was created using a two-channel SMU optimized for low current measurements. was configured to measure terminals. An FET’s I-V characteristics terminals of both SMU channels One I-V test commonly Line Regulation the output voltage. The line can be used to extract many or to a third SMU channel if it is performed on a MOSFET is the Line regulation refers to a DC- regulation percentage can then There are many types of FETs, device parameters, to study the necessary to source and measure drain family of curves (VDS-ID). DC converter’s ability to maintain be calculated from the I-V data. including MOSFET (metal-oxide- effects of fabrication techniques from all three terminals of the With this test, SMU CH1 steps the specified output voltage in semiconductor), MESFET (metal- and process variations, and to MOSFET. the gate voltage (VG) while SMU response to input voltage changes. Simplifying FET testing with semiconductor), JFET (junction), determine the quality of the CH2sweeps the drain voltage The output voltage should remain SMUs OFET (organic), GNRFET contacts. Figure 5 illustrates a Once the device is set up and (VD) and measures the resulting constant, within a few millivolts, Characterizing an FETs current- (graphene nano-ribbon), and DC I-V test configuration for a connected to the SMU, the drain current (ID). Once the two while the input voltage is varied voltage (I-V) parameters is CNTFET(carbon nanotube). MOSFET using a two-channel control software, often an SMU channels are configured over the specified voltage input crucial to ensuring it meet These FETs differ in the design of SMU (CH1 and CH2). Here, the embedded software tool, must to perform the test, the data can range. For the line regulation test, specifications and works properly their channels. Force HI terminal of SMU CH1 be configured to automate the be generated and plotted on the

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Battery Technology: Power to the People Energy storage is growing in importance for today’s applications

By: Mark Patrick, Mouser Electronics

s the roll out of billions of sensors and wireless nodes in the Internet of Things A(IoT) progresses, more attention Figure 7: In this example, drain current is shown as a function of the gate is being paid to the battery voltage of a MOSFET. technology that powers them. screen in real time. Figure 6 shows from 1E-12 to 1E-2 amps. At the same time developers of a MOSFET drain family of curves electric cars are also looking for created by using a two-channel Summary better battery solutions. SMU optimized for low current Test complexity is the enemy measurements. Once exported of engineering efficiency and Regularly changing the batteries to a .csv file, this I-V data can be productivity. As shown here, of a billion devices in the IoT imported into a spreadsheet for source measure units that represents a major challenge - in further analysis or displayed in combine the functionality of terms of both cost and logistics. table view. multiple instruments into a Consequently developers are single box can simplify testing keen to implement rechargeable Figure 1: TDK battery Another common I-VFET test this procedures, saving time and battery cells that can use energy dendrites which can cause short industrial applications that are same configuration supports is producing more accurate and harvested direct from the circuits and, in the worst case expected to last for 10-20 years - Drain Current (ID) as a function repeatable results. In the case environment, such as via solar scenario, lead to fires. The small and yet the demand for smaller of Gate Voltage (VG). For this of DC-DC converter testing, cells or thermal gradients. filaments grow during charging size and longer life continues test, the gate voltage is swept a single two-channel SMU and can eventually connect to increase. So researchers and and the resulting drain current replaces a couple of digital Lithium-based batteries have across the anode and cathode. battery companies are looking at is measured at a constant drain multimeters, a power supply, been taking over from nickel This has made it more difficult different ways of providing higher voltage. Figure 7 shows the and an electronic load. In the cadmium (NiCd) and nickel to transport cells from offshore energy density in a cell that is results of an ID-VG curve at a case of the FET characterization, metal hydride (NiMH) cells manufacturing plants, due to the safer to use. constant drain voltage. However, SMUs are a simpler, cost-effective in recent years by providing a risk of the batteries igniting in in this case, the generated data alternative to test setups such as higher energy density levels. the hold of cargo planes. Applying Solid State Technology was exported to a file and plotted sensitive ammeter and multiple However, these come with their One way is to take a solid state on a semi-log graph. This test voltage sources or a dedicated own challenges, especially when Lithium cells also have a limited approach. Current lithium can be easily reconfigured to semiconductor characterization placed in an industrial or electric number of charging cycles. This polymer cells have an energy step the drain voltage as the gate system. vehicle context. is fine for consumer applications, density of around 160Wh/l and voltage is swept. The ID-VG data such as mobile phones that use a thick polymer liquid that shows the many decades of drain Tektronix Rechargeable lithium batteries are replaced every two to three allows the lithium ions to move current that the SMU measured, www.tek.com are prone to the development of years, but poses a problem for but which can leak and allow

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using a 3D ball of graphene and need to be packed efficiently to the molecular bonds. “We are close contact between the silicon dioxide to coat both the increase the battery capacity. The combining a nanostructured battery's three layers: the anode, anode and the cathode. This arrangement of aluminium ions cathode and a new understanding consisting of solid metallic doubles the energy density and inside graphene is critical for of the magnesium electrolyte,” sodium; the cathode, a mixed stops the growth of dendrites. better battery performance.” said Yan Yao, Associate Professor sodium chromium oxide; and the The technology has been of Electrical Engineering at electrolyte, the closo-borane," patented and is set to appear In Spain, a Euro 3 million the University of Houston, said Léo Duchêne, a researcher in batteries for IoT and mobile research project has started which is heavily involved. This at Empa's Materials for Energy phones soon. developing a new type of allows batteries with a cathode Conversion Laboratory. Sheffield- rechargeable solid state battery capacity of 400mAh/g (up based start-up Faradion is also Other Possibilities also using aluminium. The from 100mAh/g for earlier working to commercialise its Researchers are, however, also sulphur-aluminium battery magnesium batteries) and twice liquid sodium battery technology looking at many other materials with advanced polymeric gel that of commercial lithium-ion for electric scooters and cars, for battery cells, from aluminium electrolytes (SALBAGE) project batteries (which generally have a while Oxis Energy in Oxford and sodium to magnesium could produce a solid state capacity of 200mAh/g). Though has developed lithium-sulphur and graphene. The staff at battery with an energy density admittedly, the voltage of the cells for the same types of the Clemson Nanomaterials over five times that of today’s new battery remains low at about applications. Institute, in South Carolina, for lithium-ion cells. It is led by 1V, compared to 3V to 4V for instance, have developed an Spanish battery developer lithium-based batteries for IoT Conclusion Figure 2: Toshiba SCiB batteryy aluminium battery that could be Albufera Energy Storage, in applications. A lot of engineering effort is the growth of dendrites. This currents of a few mA to be cheaper and more reliable than Madrid, along with several going into replacing current also prevents the cells being drawn and comes in a compact lithium-ion technology. Apparao European companies and Sodium is another material with liquid lithium-ion polymer soldered to a board in a surface EIA 1812 package. It is aimed Rao, Professor of Physics at universities. The new battery is potential for next generation batteries, in order to better mount reflow process, thereby predominantly at applications Clemson University and Director expected to have a high energy batteries. Switzerland scientists attend to both IoT and electric increasing production costs. such as real-time clocks, of the Clemson Nanomaterials density of 1000Wh/kg and low have developed a prototype of a vehicle applications. Solid state Bluetooth beacons, wearables Institute, has used aluminium price (at around 60% of today’s 3V solid state sodium battery with lithium designs that can be As the name suggests, solid state and IoT nodes using energy foil and a graphene anode to lithium-based cells). the potential for higher energy surface mounted and versions batteries have solid layers and so harvesting. construct a battery that can densities than lithium cells. "We that charge quickly in electric inhibit the growth of dendrites. operate over 10,000 cycles and Magnesium is an increasingly still had to find a suitable solid vehicles are already coming However, getting the ions to Toshiba has likewise developed a has an energy density of 200Wh/ popular choice for battery cell ionic conductor that, as well as to market. Research on other move easily between the anode solid state battery. This employs kg. technology too. Researchers at being non-toxic, was chemically materials, such as sodium and and cathode has significant a titanium niobium oxide anode the University of Houston have and thermally stable, and that sulphur, are in early stages difficulties associated with it. material that can be charged in a The battery cell uses thin found a way to make magnesium would allow the sodium to of market acceptance, while These need to be addressed - as matter of minutes, and is aiming sheets of graphite called few- batteries that are intrinsically move easily between the anode entirely new cells with much the easier they move, the faster this at electric vehicles. The layer graphene as the electrode safer and twice the capacity of and the cathode," said Hans higher performance levels are the cell will charge. SCiB cell has double the storage to store electrical charge from current lithium ion batteries. Hagemann, Professor of Physical on the horizon. All of these capacity by volume of the current aluminium ions present in the This project has already spanned at the University of Geneva. The aim to provide higher density, TDK for example has launched generation of lithium batteries electrolyte. several years and involved researchers discovered that a longer charging cycles and faster the first solid state lithium cell with graphite-based anodes scientists from three universities boron-based substance, a closo- charging, without the risks of that can be surface mounted. (where a 20Ah cell has an energy “We knew that aluminium ions and three leading US scientific borane, enables sodium ions fire, in order to provide system The cell uses ceramic layers that density of 176Wh/l) and will start could be stored inside few-layer laboratories. The key is expanding to circulate freely. As the closo- designers with the energy they allow the ions to move, and can shipping next year. graphene,” said Ramakrishna a titanium disulphide cathode borane is an inorganic conductor, need. be recharged up to 1000 times. Podila, Assistant Professor to allow magnesium chloride it removes the risk of the battery It has a capacity of 100µAh at a Samsung has also been working of Physics who also worked molecules in whole, rather than catching fire while recharging. Mouser Electronics nominal voltage of 1.4V allowing on new forms of lithium cell, on the project. “But the ions having to use energy to break "The difficulty was establishing www.mouser.com

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Technology-Driven Optimization for Power and Thermal Tradeoffs How small architecture changes early in the design phase can have a huge impact on the power consumption of the end product By: Frank Schirrmeister, Cadence Design Systems

raditionally the key concerns and Figure 2: The need for “deep cycles” Toptimization get to, they allow dealing with data in a data stream. However, back-annotated timing, users targets in chip a reasonable amount of data users often focus completely on have to take into account development have at high simulation speed but functional verification during significant simulation times. been summarized limited accuracy. this phase. Also, simulation as “PPA”— times are becoming significant Once design teams have performance, As the design proceeds towards and the actual effort to design reached the actual layout phase, power and area. implementation at the register- the RTL often prohibits focus on which leads to the delivery Depending on the Figure 1: Highest optimization potential exists at the system-level transfer level (RTL), the number energy optimization at this level of a GDSII tape for actual application domain, the relative well, where in some cases, for design. Micro architects who of options to reduce the energy of abstraction. implementation, sufficient data weighting of those three design instance AnTuTu, benchmarks take an algorithm defined in C consumption is still quite high, is available to allow accurate objectives can vary greatly. simply started dropping to lower or SystemC and decide how to allowing reasonable overall After logic synthesis for the simulation and estimation of In mobile devices, power has levels at a later time during implement it face various high- leverage. Specific areas of the gate-level netlist, dynamic energy consumption. Depending been key for quite some time. operation as thermal limits impact areas for low-power design can be dynamically energy consumption can be on the estimates at this level In fitness trackers, medical were reached and some of the optimization, such as bit-width switched to low-power modes, determined fairly accurately of abstraction, design teams devices, and other products processing power needed to be selection, tradeoffs between trading performance versus based on the design activity. can still do transistor sizing for the IoT edge, power may switched off. performance and voltage energy during execution. At this level, design teams can and layout rearrangements to be so scarce and important and energy consumption, Popular methods are reduced utilize optimizations minimizing achieve optimization based on that harvesting of power As illustrated in Figure 1, looking optimization of the design clocking or full clock gating of the capacities that have to be placement and interconnect. during operation is critical. In at the various components activity, trading area versus areas in the design. Optimized driven by the most active nodes The accuracy at this level of contrast, for wall-outlet-powered of a chip from analog and energy consumption, memory resource sharing, isolation of in the design. Also, energy abstraction is very high, but the devices like servers and most mixed-signal circuitry, control optimization, clock gating, operands and optimized coding consumption can be optimized amount of data to be processed consumer electronics, power hardware, dataflow hardware, voltage scaling and hardware/ of controller and bus states using a balance of path delays and the simulation speed are may be less of an issue, but memory, and software, the last software tradeoffs. For instance, can contribute to reduce the to avoid spikes and spurious so limited that typically only a thermal effects become critical. three typically have the biggest if specific functions can be capacities to be switched. In transitions and re-timing. The small number of test vectors Also, can a given package deal impact on power consumption— moved from software to principle, architecture changes accuracy of power estimation can be used for analysis. The with the energy consumption especially at higher levels hardware at the architectural are still possible at this level. For is quite high at this level of leverage on energy consumption appropriately or will parts of the of abstraction. Designers level, significant power example, a user may change the abstraction, but the amount of is comparatively low as no devices have to shut down to make several decisions that reduction can be achieved. number of multipliers to reduce data to be dealt with increases major design changes, such as prevent overheating? This links significantly influence the System-level models are switching via utilization of greatly. Even if the gate-level adjustments to the number of back to mobile applications as power consumption of the required but relatively easy to correlation between subsequent simulation is performed without arithmetic resources, can be

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a design, including the software running on its processors, users are at risk of getting stuck in a local minimum. Deep cycles are needed to find the actual worst-case power consumption.

Using emulation in combination with power estimation from RTL or gate-level, it is possible to bridge abstraction levels today. With emulation solutions, like the Cadence Palladium Z1 Enterprise Emulation Platform, users can collect large amounts of activity data in a relatively short amount of time and connect them to implementation flows. Even though emulation allows execution in the MHz range when compared with simulation that runs in the Hz range, identifying the correct hotspots is best achieved by starting with more abstract, course- grain activity information, like raw toggle counts Figure 3: Cadence Dynamic Power Estimation Flow for the design, where each toggle counts as one made anymore. point in time. In contrast, when simulation cycles including to achieve early-stage estimation. the most accuracy is available software execution, for example, Bottom line, power optimization at the layout level, the impact of with accurate information After refining the area of interest, weighted faces a dilemma: While decisions changes based on that data is derived from semiconductor toggle counts can be used. They operate with at higher levels of abstraction relatively small, and simulation technology library definition. weights on different nets, for instance, when at the system level have the times take a very long time. To treating a memory write-enable toggle as more TDK Technology highest impact, they are made address that dilemma, users Bridging Abstraction Levels significant for power consumption than a NAND based on the least-accurate data need to be offered techniques As illustrated in Figure 2, if not gate input toggle. This achieves higher accuracy. Advancing power available for the design at that that allow combination of deep enough cycles are executed for The highest accuracy can ultimately be achieved using the SAIF toggle-count format at fine-grain accuracy. This format can then be consumed by solutions. power calculators like the Cadence Joules RTL Rare-earth magnets Varistors and Power Solution, which takes low-level technology with high magnetic surge arresters data from .lib definitions into account. fi eld strength for wind with high surge power generators capability Figure 3 shows the resulting design flow and an example of a power profile debug environment that includes toggle count and visualization of a power shutoff. Design teams can shift the power optimization steps to a much earlier time in the design cycle using either: (1) A combination of activity data derived from the RT-level with estimates of power consumption from RTl using technology information in .lib files, or (2) Using EMC fi lters and Aluminum electrolytic activity information derived from the gate-level sine-wave fi lters for and fi lm capacitors Figure 4: Checks to be performed during a power off/on scenario with annotated power information to which .lib currents up to 8 kA for high ripple currents

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DU180507_TDK_T123_IND_E_PSD_Europe_Mag_102x273.indd 1 09.04.18 16:02 POWER DESIGN

files can be annotated directly. overlaying low power on the platform requires a change to This saves expensive redesign verification problem. It becomes existing user code to include cycles as opposed to discovering very desirable to enlist the that IEEE 1801 power intent file Special Report: power issues that need to be raw computational power of during the compilation stage, corrected at a later stage of the emulation, augmenting what can and the rest of the flow is fully Automotive Electronics + project. It also allows designers be done in simulation. automated. to optimize power with software running on processors that A typical functional test would User Experiences Infotainment are part of the design and can be augmented to include the For dynamic power analysis, heavily impact the dynamic power control signals. For power one recent example was shared power consumption. shutoff verification, for instance, at CDNLive in Silicon Valley the cycles for asserting isolation in a presentation by Theodore Utilizing Standard Formats begin the sequence, followed by Wilson, technical lead for Like IEEE 1801 state retention, and then finally Architecture Co-Verification at IEEE 1801/UPF is an IEEE a power shutdown of the domain Microsemi, called, “Rapid Turns standard that specifies power must be asserted to verify with Palladium and Joules”. intent using either a separate operation. Figure 4 calls out a The key metric Microsemi was file via TCL-style commands or number of checks that ought to trying to optimize was “power power intent written directly in be performed. analysis is throughput—the the hardware description via time from activity trace to language attributes and HDL When evaluating emulation actionable power reports.” By packages. The standard defines support for IEEE 1801, users combining the Palladium Z1 the different power domains in should check for specific platform with Joules power a design and various tools, such capabilities that have specific estimates, Microsemi was able as simulation and emulation, implications to them. For to do gate-level runs as soon can consume IEEE 1801 instance, memory randomization as RTL was functional… all of compliant code to help users during shutdown and power- it early, accurate and precise. represent the power intent. up, control over the read value Other customers, such as Texas When considering a design with during the power-off state, non- Instruments, previously reported four power domains—three of volatile memory state retention, results of the emulation to which are switchable and one and the freezing of data on implementation flow to be that is switchable but also has retention are important when within 96 percent of their Inside: high- and low-voltage states— it comes to making the low- expected power consumption. By users will have to test nine power verification repeatable. doing longer runs in emulation basic states and 24 modes of Users should be aware that in when compared to simulation, 26 operation. emulation—such as when using they were able to detect Automotive Infotainment System Designs Get Easier... the Palladium Z1 platform— unexpected power conditions This testing can be done in a 10%-20% capacity overhead as the design was run on Transient Protection Solutions in Automobiles... 31 simulation and emulation. associated with IEEE 1801-driven emulation with actual Although some of these modes low-power verification exists software for real use-case Wide Bandgap SiC Devices for Auto Power Electronics... 37 of operation may not be due to the automatic insertion scenarios. consequential, when paired with of logic to handle power domain Microcontrollers Evolve to Support BLDC Automotive Needs... 40 hundreds or even thousands of management. The emulation www.cadence.com functional tests, one can begin workflow for IEEE 1801 power More information on Microsemi to understand the impact of verification in the Palladium Z1 case study http://bit.ly/2J0Cspy

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Another key to operating an in DC-DC converters comes from A Simple Solution integrated power management the switching edge rates of its Historically, many PMICs have Automotive Infotainment device in a high ambient internal power MOSFETs. These not possessed the necessary temperature environment is for edge rates should be controlled to power to handle these modern System Designs Get Easier the device to self-monitor its reduce radiated emissions. systems and microprocessors. own die temperature and report Any solution to satisfy the auto- Multi-Output Power Management ICs now have the power and levels when its junction temperature Many of today’s embedded motive power management IC of integration to handle modern automotive systems is getting too high so that the systems and advanced design constraints as already out- system controller can make an processors require controlled and lined must combine a high level By: Steve Knoth, Analog Devices, Inc. intelligent decision on whether choreographed sequencing as of integration, including high- to reduce power to the load(s). power supplies are powered up current switching regulators and s product form factors Nevertheless, demand for this OEMs. Starting with the wide Operating system software can and applied to various circuits. LDOs, wide temperature range of are decreasing, same combination of high operating temperature range, do this by turning off less critical Allowing for system flexibility and operation, power sequencing and demand for their power efficiency and processing power management ICs are functions or by turning down a simple approach to sequencing dynamic I2C control of key param- functionality and performance has spread to non- challenged on two fronts. First, the performance in processors not only makes the system design eters with hard-to-do functional Afeatures continue to increase. portable applications. A couple power conversion - even when and other high power functions easier, but it also enhances blocks. Furthermore, a device Furthermore, the industry trend of examples include automotive highly efficient - must dissipate such as displays and network system reliability and allows for a with high switching frequency for sophisticated digital ICs infotainment systems and some level of power as heat. communications. single PMIC to handle a broader reduces the size of external com- such as microprocessors (uP) other embedded applications, When several DC-DCs and LDO range of the system than just a ponents and ceramic capacitors and microcontrollers (uC) or both of which demand similar regulators are packed into a single The environment within a current specific processor’s requirements. reduce output ripple. This low field programmable gate arrays levels of power efficiency and device, the combined power vehicle’s dashboard is crowded ripple combines with accurate, (FPGAs) that power these processing horsepower. In all dissipation can be significant, with electronics. Adding to products continues to lower cases, a highly specialized, high easily approaching two Watts or this crowding are radios from their operating voltage while performance power management more. Typical PMIC packages Bluetooth to cell phone based simultaneously increasing their IC (PMIC) is necessary to such as the 6mm x 6mm 40 pin, network connectivity. Therefore, amperage. Microprocessors properly control and monitor the exposed pad QFN have a thermal it is imperative that any additional are among the most popular of microprocessor’s power so that resistance of 33°C/W resulting entries to this thermally these to design in, and there is all of the performance benefits of in a junction temperature rise constrained environment not a growing list of power efficient these processors can be attained. in excess of 60°C. When this is contribute excessive heat or EMI. types. They are designed to Further, as the electronic content combined with the additional There are strict Electromagnetic provide low power consumption of automobiles continues to challenge of a wide ambient Compatibility (EMC) requirements and high performance processing dramatically increase, so too has operating temperature range, the which cover radiated and for a wide range of wireless, the use of microprocessors as maximum junction temperature conducted emissions, radiated embedded and networking the work horse of various control of the PMIC can often exceed and conducted immunity or applications. systems within the vehicle. 125°C. Even in body electronics, susceptibility, and Electrostatic not under the hood, the ambient Discharge (ESD). Being able to The original intent of these Automotive PMIC Challenges temperature inside a sealed conform to these requirements processors was to enable Electronic systems designed plastic electronic control module affects the performance aspects OEMs to develop smaller and for automotive applications are can reach 95°C. Due to these of a PMIC design. Some are more cost-effective portable challenging for many reasons, temperature challenges many straightforward, such as the DC- handheld devices with long including the wide operating PMICs rated for 85°C, or even DC switching regulators must battery life, while simultaneously temperature range, strict EMC 125°C, are not sufficient for operate at a fixed frequency well offering enhanced computing and transient requirements, as sustained high temperature outside of the AM radio band. performance to run feature- well as the high quality levels operation. However, another common rich multimedia applications. demanded by automotive radiated emission source found Figure 1: LTC3676-1 Simplified Typical Application Diagram

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regulated 5V or 3.3V rail off the The device is available in a low profile 40-pin 6mm x TRahck Moeunti ngOnly 1U Need. system or battery voltage. 6mm x 0.75mm exposed pad QFN package.

A High Power, Power The LTC3676 Power Management Solution for Application Management Solution Processors can solve the automotive infotainment system The LTC3676/-1 are complete design challenges outlined above. The LTC3676HUJ PMIC Benchtop power management solutions is available in a high temperature (H-Grade) option with for Freescale i.MX6 processors, a junction temperature rating from -40°C to +150°C, easily ARM-based processors and satisfying the high temperature automotive operating other advanced portable requirement. The IC includes a thermal warning flag and Acopian 1U Power Supplies. microprocessor systems. interrupt specifically for junction temperature monitoring The LTC3676/-1 contain four and also includes a hard thermal shutdown for reliable synchronous step-down DC/DC protection of the hardware, should power dissipation be Everything you want, converters at up to 2.5A each for mismanaged, or in the event of a severe fault condition. core, memory, I/O and system on- nothing you don’t! chip (SoC) rails plus three 300mA The LTC3676 PWM switching frequency is specifically These power supplies are offered in both single linear regulators for low noise trimmed to 2.25MHz with a guaranteed range of 1.7MHz output (any voltage from 1vdc to 135vdc) and Figure 2: The LTC3676 Startup Sequence analog supplies. The LTC3676-1 to 2.7MHz. Its internal regulators can also be set to wide-adjust output (any range from 0-5vdc to fast response regulators to satisfy meeting the rigorous automotive configures a 1.5A buck regulator a forced continuous PWM operating mode to prevent 0-135vdc) models, with current capabilities up to demanding voltage tolerances environment including radiated for source/sink and tracking operation in pulse skip or burst-mode even at light loads. 70A. Metering and digital interfaces including of 45nm type processors. Such emission suppression, although operation to support DDR This not only keeps the frequency fixed but also further RS232, RS485, Ethernet, and USB can be specified, power ICs must also be capable of the input voltage is typically a pre- memory termination and also reduces voltage ripple on the DC-DC output capacitors. in addition to many other available options. All units adds a VTTR reference output are UL60950, UL508, CE and ROHS Certified. And, for DDR. These two pin features Suppressing Radiated & Conducted Emissions since all features come a la carte, it’s a cost-effective replace the LDO4 enable pin and Since there are 4 switching regulators onboard the solution that’s a perfect choice for engineers and feedback pins of the LTC3676. LTC3676, each has an associated reactive device buyers alike! Visit www.acopian.com to shop millions LDO4 is still programmable by (inductor) to be concerned about. One possible solution of reliable power supplies, made in the USA and I2C. Supporting the multiple is to shield the LTC3676 area to prevent EMI from being shipped within 3 days. regulators is a highly configurable emitted. Besides being expensive and heavy, this does power sequencing capability, not solve the problem of contamination by any wires that dynamic output voltage scaling, might be connected to the power supply area. It is better a pushbutton interface controller, to use source suppression and antenna elimination. plus regulator control via an I2C interface with extensive status and Source suppression necessitates good layout/ fault reporting via an interrupt component selection (and internal IC design) to prevent output. The LTC3676 supports the generation of radio frequency energy. It is often i.MX6, PXA and OMAP processors necessary to use shielded inductors and to place those with eight independent rails at inductors further away from the LTC3676 than the output appropriate power levels with capacitors. This is because the AC currents circulate dynamic control and sequencing. from the LTC3676 through the inductor, through the Other features include interface output capacitor, to ground and back to the LTC3676. signals such as the VSTB pin that It is clear that wide traces, preferably area fill, should toggles between programmed run be used to connect the ground of the output capacitors and standby output voltages on to the ground of the LTC3676 and to the ground of the Figure 3. The LTC3676 Power-Down Sequence up to four rails simultaneously. PVIN input decoupling capacitors also.

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The LTC3676 also provides some create slot antennas. But other awareness, even when the engine tools for source suppression. Its obstacles, such as changing is not running. DC-DC converters specifically layers, contribute some energy in Transient Protection Solutions include a dv/dt control feature the EMI signature and should be Finally, the LTC3676 supports which slows down the switching minimized. Ideally the top and simple and effective power in Automobiles edge rates to reduce radiated bottom layers should be all, or sequencing which can be handled emissions. Since the buck mostly, ground plane, with the through serial communications ESD-Safe MLCCs, Slow Transient Wave-Rated MLCCs, and regulators are synchronous, both signal layers flowing internally. or via pin strapping where power the rise and the fall time are both Since this is usually not practical, supply output voltages are tied Multilayer Varistors controlled. A slow edge rate of some thought needs to go into to enable pins in the desired By: Ron Demcko, Fellow, AVX Corporation about 3ns rise/fall, was selected to how the ground plane will be turn-on sequence. Internally each both pass emission requirements connected prior to commencing enable is delayed micro seconds hanks to and still limit switching losses, layout. For example, it is not a to further time stagger the modern which helps to optimize power good idea to put the LTC3676 startup sequence. This feature technology, converter efficiency. Each of the into a corner or tab on the PCB. is supported with precision low passenger 4 buck switching regulators in the This will make it very difficult to voltage enable thresholds so the Tvehicles are now safer, LTC3676 default to this 3ns edge properly route the ground plane. sequencing is possible even with more enjoyable, and rate control mode, but can also be However, it is a good idea to route output voltages as low as 0.43V. more efficient than ever. individually set via I2C, to a faster the high circulating current areas Each supply voltage output is Today’s automobiles 1ns rate, to improve efficiency, if of the LTC3676 first, to ensure the also soft-started to limit inrush utilize incredible limited edge rate and emissions most optimum layout possible. current and produce clean amounts of computing control is not required. voltage transitions. See Figure 2. power to improve If EMI control is planned and the overall driving In addition to switching time executed with the concepts of The LTC3676 also includes experience in several control, the LTC3676 offers some source suppression and antenna easily programmable power- different ways. For Figure 1: MLV (left) vs. TVS diode (right) temperature derating other EMI suppression tools. The elimination in mind, it is possible down sequence control. The example, arrays of sensors and nature of their high-reliability for each and every automotive frequency of the buck regulators to create a full power system that IC includes two registers for dedicated processing units now performance helps support the application. can be changed from 2.25MHz to is a good EMI neighbor without initializing a power down monitor and make use of vast argument that these increasingly 1.12MHz. Also, to minimize the increasing product cost or weight. sequence configuration which amount of data from systems prolific devices are now more This article examines two input ripple, which can end up will be followed at the next turn- spanning cabin entertainment susceptible than ever to automotive transient voltage radiating through the power input More Key Features off event or overpower fault electronics to critical underhood transient voltages. Automotive control options, transient wiring, the buck regulators can be The LTC3676 fully satisfies the condition. Each regulator (DC- modules. Multiple central design engineers generally use voltage suppression clamps staggered between two different automotive ESD requirements of DC and LDO) can be pre-set processing units now employ shielding and routing methods (i.e., multilayer varistors) clock phases. 2kV HBM and 1000V CDM which to any one of four time slots high-speed networks to transmit to redirect transients, transient and integration capacitors, is another key requirement for for shutdown. Each regulator data to even larger and more voltage suppressors to clamp the and compares and contrasts The LTC3676 is also capable of approaching zero defects in the output includes an internal pull- powerful processors that profile, effects of incoming transients, multilayer varistors, ESD-Safe™ providing considerable power, in automotive assembly process. down resistor that is engaged prioritize, and control numerous or integration capacitors to MLCCs, and slow-pulse capable excess of 10W. This can result in Further, the IC has very low when disabled to guarantee the sub systems. In addition, capture transient voltages and multilayer ceramic capacitors. substantial circulating currents standby current consumption, controlled discharges as shown automobiles now utilize RF slowly release their energy back and so it is imperative to provide typically 12uA, which is desired in Figure 3 and a low starting links to communicate with both into the circuit at levels below Performance Considerations an uninterrupted path for this in “always on” automotive point for the next turn-on one another and surrounding the susceptibility limit. However, The ideal method of transient current to circulate. In particular, navigation, security and safety sequence. infrastructure. due to the varying nature of voltage suppression is to slots in the ground plane, systems which must maintain these device’s cost, size, and clamp the transient voltage which force the large circulating continuous power to real time Analog Devices The complexity of automotive performance limitations, there with a transient voltage currents to flow around them, clock circuits for temporal www.analog.com ICs and the often critical is no “one size fits all” solution suppressor (TVS). Of all the

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Transient Voltage Control via Multilayer Varistor (MLV) Clamping Multilayer varistors are zinc oxide (ZnO2) ceramic semiconductors that exhibit nonlinear voltage- current (VI) characteristics in the presence of an electric bias. The number of grains between the Figure 3: The human-body model (HBM) is one of the three most common multilayer conducting electrodes models that can be used to simulate transient sources that could inject ESD determines the breakdown voltage, which is defined as the Figure 2: A typical CAN circuit with two MLCCs and two diodes (left) and a typical CAN circuit with either two MLVs into a victim or one two-element MLV array (right) combination of qualities is fairly TVS devices available on the is best suited for non-critical CAN circuits due to the fact common. In most engine control market, multilayer varistors automotive applications. In that several series can operate units (ECUs), there is typically an (MLVs) are one of the best instances where communication at 150°C without the need for 80/20 need for ESD integration choices due to the fact that bus structures need transient derating. So, as CAN interfaces capacitors versus MLVs on the they are small, lightweight, control, MLVs are a more and other communication buses pins. For example, a 300-pin ECU and capable of both clamping effective transient voltage continue to expand their roles would have a 240:60 ratio of voltages in their on-state and solution, as the magnitude of to underhood applications, the integration capacitors to MLVs. acting as an electromagnetic capacitance needed within an case for the use of MLVs will only interference (EMI) filter in their integration capacitor would become stronger. ESD Models off-state. Additionally, MLVs cause signal data skew. ESD is a sub-nanosecond rise- do not have the same severe In circuits that utilize ICs time event that is generated by power derating limitations Modern vehicles have several with on-chip protection or the charge transfer of materials as TVS diodes do (Figure 1). dozen CAN interfaces that ICs integrated within a PCB in the tribo-electric material This feature is increasingly require transient voltage control. or module, or in applications series. ESD can be either positive Figure 4: MLV voltage-current (VI) curves important in automotive LED Figure 2 illustrates a typical where automotive circuits or negative in polarity, contact- into a victim, but the three most 1mA current conduction point on drivers and engine electronics, CAN circuit both before and employ lower cost, slower, and or air-discharge, and repetitive common are the charged device the VI curve. Clamping voltage is as these applications are after the implementation of less complicated ICs, the ICs or random in nature. model (CDM), the machine defined as the maximum voltage frequently subjected to operating CAN MLVs. In this example, an will exhibit at least a moderate model (MM), and the human- measured with an 8x20µs temperatures approaching or MLV is connected from both the degree of inherent ESD An ESD event is typically body model (HBM). waveform applied at a specific even exceeding 125°C. CANH and CANL lines to the survivability. So, ESD integration modeled by a capacitor current magnitude defined by ground and is used to provide capacitors can provide effective charged to a particular voltage ESD-Safe™ MLCCs are generally the energy rating of the part. In some cases, ICs have a level EMI filtering in the varistor’s off- transient voltage protection in level in series with a current- intended for use in IEC 61000-4- Another parameter of MLVs is of on-chip protection or are state and to provide bidirectional these types of circuits. However, limiting resistor, both of which 2 applications subjected to HBM operating voltage, which is the located deeply within the inner protection for the IC when it is important to understand are discharged at particular strikes (150pF, 330Ω), but not steady-state voltage that can be portion of a PCB or module. In ESD or other transients are that these solutions are only repetition rates to simulate a exclusively in contact discharge indefinitely applied to the MLV these instances, an integration present, making it an effective effective in the case of short- certain number of real-world mode (Figure 3). Although there without causing an increase in capacitor can often be used to replacement for both the EMC waveform incidents upon transients on the device under are many common transients the specified leakage current of attenuate the front-end, rise- capacitor and the bidirectional fairly rugged ICs in non-critical test (DUT). There are several that are slow in speed, ESD-Safe the part. time effects of the transient. This diodes used in the circuit with a applications that can withstand models that can be used to MLCCs are primarily intended for type of protection, electrostatic single MLV. MLVs are also well large amounts of capacitive simulate the various transient use in fast transients hardening. Figure 4 shows the VI curve for discharge (ESD) integration, suited for use in automotive loading. Luckily, though, that sources that could inject ESD

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Figure 5: The conservation of charge applies to the capacitance voltage product of the ESD model and the combined capacitance of the ESD model plus the ESD integration capacitor. an MLV acting as a TVS clamp. damage. Although this can be expected value of a standard X7R MLVs offer advantages over other an effective design practice, capacitor can result in a much TVS clamps, such as diodes, engineers often overestimate the higher voltage at the IC or device and significant advantages over capacitor's performance due to that needs to be protected. ESD MLCCs, including large in-rush its significant value drop upon capacitors can be an effective current capabilities, high-energy the applied ESD event. weapon in the control of ESD transient voltage suppression, events, but designers should off-state bulk EMC capacitance, Generally speaking, the amount exercise extreme care during the an extremely low failure-in- of capacitance drop for NP0 device selection process. time (FIT) rate, and ease of dielectrics is negligible. However, assembly. These benefits make the amount of capacitance The conservation of charge MLVs attractive solutions for drop for X7R capacitors can be applies to the capacitance circuit protection in advanced 50% or greater. This value also voltage product of the ESD automotive systems. varies from manufacturer to model and the combined manufacturer and on a lot-by- capacitance of the ESD model Figure 7: The relative protection against positive and negative 2kV transients (top), 4kV transients (middle), and 8kV tran- Transient Voltage Control via lot basis within any particular plus the ESD integration sients (bottom) that a 4.7nF X7R dielectric MLCC, a 100nF X7R dielectric MLCC, and an 18V MLV provided the DUT. the model is charged, C is The original charge of the ESD and charged to 8kV, and the MLCC Integration manufacturer, as ESD voltage capacitor (Figure 5). This can icap the capacitance value of the model is split between the ESD integration capacitor is rated coefficient is not characterized be represented by the equation integration capacitor, and Vic is model's capacitance and the for 1,000pF, the expected surge Many transient voltage control on a lot-by-lot basis for standard Cmodel x Vmodel = (Cmodel + Cicap) the voltage that the IC (or device ESD integration capacitor. For voltage at the IC would be designs utilize a capacitor at the capacitors. x Vic, in which Cmodel is the to be protected) experiences. example, if the capacitor in the approximately 1,044V. I/O pin to integrate the voltage capacitance of the ESD model, ESD model is rated for 150pF and protect the IC from ESD The capacitance drop from the Vmodel is the voltage to which ESD Capacitor vs. MLV HBM ESD Testing Human-body model (HBM) ESD tests were performed on two common MLCCs and an MLV in an effort to determine the effect of each device on an ESD waveform of varying magnitude in an IEC 61000-4- Figure 6: An optimized ESD component test fixture (left) and equipment set-up Figure 8: Technical specifications for ESD-Safe MLCCs and MLVs 2 application. In this test, the

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Wide Bandgap SiC Devices for Auto Power Electronics SiC technology and devices are becoming more mature with costs also coming down By: Dennis Meyer, Applications Engineer, and Jason Chiang, Strategic Marketing Manager, Microsemi Figure 9: Dissipation factor (DF) and insulation resistance (IR) values for low transient waveform pulse MLCCs DUT was soldered to a test increases as the transient voltage B, 3A/B, 4, and 5A/B, along with utomotive OEMs and card terminated with an SMA increases, while the MLV exhibits GS95003-2 load-dump transients. their suppliers have connector that connected to an a relatively constant clamping State-of-the-art, slow-wave been on the high entry port on a faraday-shielded voltage regardless of the ESD MLCCs are available in 0603 power, high growth ve- Ahicle electrification path for hybrid 40dB attenuator that connected transient magnitude. to 1210 case sizes, capacitance to a TDS 784 oscilloscope. Test ranges spanning 1nf to 4.7µf, and electric vehicles (HEVs)/electric set-up and definition is shown in These tests illustrate that larger- with dissipation factor (DF) and vehicles (EVs) and beyond even Figures 6. value capacitors will integrate insulation resistance (IR) values to electrification of busses, trucks, the transient voltage to a as shown in Figure 9. trains and more electric aircraft The test proceeded with the lower voltage level. However, (MEA). With high power demands contact discharge of positive and as mentioned, there is a Summary beyond the efficiency and reliability negative transients of 2kV, 4kV, practical limit to the amount of Today’s automotive design that silicon IGBTs and MOSFET and 8kV ESD strikes to the DUT. capacitance loading that a circuit engineers have a wide range devices can offer, wide bandgap The resulting voltages captured may allow. Voltage lines have of transient voltage control silicon carbide (SiC) solutions are are representative of the ESD virtually no capacitance limit, solutions to choose from and on the cusp of huge growth within voltage magnitude at the port while signal and data lines have can match various solutions to the transportation sector. Various of the device to be protected. a concrete value of integration individual application demands. market reports forecast growths The graphs pictured in Figure 7 capacitance they can handle MLVs exhibit significant to 40 percent CAGR after 2020, Figure 1: RDSon vs. Temperature of Mocrosemi’s NextGen 1.2 kV, 40 mohm illustrate the relative protection before experiencing signal electrical, physical, and reliability where SiC power discretes and SiC MOSFET (MSC040SMA120B). of a 4.7nF X7R dielectric MLCC, degradation. advantages over TVS diodes module solutions are increasingly evolved to the point where SiC Some of the SiC benefits over sili- a 100nF X7R dielectric MLCC, and integration capacitors, and being adopted for mainstream products are more efficient and con devices include: and an 18V MLV, and the The following table depicts the testing has shown that ESD-Safe automotive applications like DC- highly competitive (at the system • SiC MOSFETs and diodes difference between integration range of commonly available MLCCs can be used to effectively DC converter, external/onboard level) when compared to silicon both parallel easily. This is and clamping devices. ESD capacitor and MLV sizes. control ESD transient waveforms charger and powertrain traction devices. SiC devices allow use of an advantage in high cur- in certain applications as well. control/motor drive. higher switching frequencies, re- rent modules like those used The 2kV graph shows the Slow Transient Waveform MLCCs Newer solutions include slow sulting in more compact designs. in traction drives. Figure 1 effect of positive and negative There are also MLCCs especially transient wave MLCCs, which SiC technology and devices are SiC MOSFETs are inherently more shows a normalized RDSon waveforms on all three of designed to survive slow have been proven to survive ISO becoming more mature with costs efficient than IGBTs, the workhorse vs temperature with a 1200V these devices. Since both the transient waveform injections. pulses. also coming down with 6-inch of power electronics, thus allowing MOSFET. The temperature MLCCs and MLV are non-polar, These devices are designed and wafer production. The quality and use of smaller magnetics and heat dependence is less than that the graph is symmetrical. The tested to suppress transients AVX supply of wafers in the industry sinks advantageous toward lower of silicon devices. integrated voltage of the MLCC including ISO 7637 pulses 1, 2A/ www.avx.com and the understanding of SiC system size/weight/cost. • SiC Schottky diodes are ca- devices by device engineers have pable of operation in the

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(HTGB) for 1,000 hours at UIS to the point that the die heats High Stress Power Cycling package thermal resistance and 100 percent rated gate voltage. to its upper temperature limit. Microsemi device testing includes the specified resistance between This is an important test with artificial aging by power cycling. manufacturers. Complicating this SiC. Fabrication of a stable SiC Where SiC differs is that the UIS MOSFETs can be artificially aged is discrete device designs usually MOSFET gate has been one test may evolve into part of a by power cycling devices over a require an insulating thermal in- of the biggest challenges with test for long-term degradation of wide temperature range. With terface. Most are very thin which SiC. the device structure. A metric of a properly designed system the presents a relatively high ca- • High temperature reverse bias degradation may evolve by first long-term reliability of a device pacitance between the back metal (HTRB) for 1,000 hours at 100 screening a population of devices can be assessed quickly. This and the heatsink. With discrete percent rate voltage. This also with UIS, subjecting them to is a test of a packaged device’s devices ceramic insulators may is a challenging test with SiC stress, and then again subjecting metallization, the die bond and be considered. Modules do very because of the gate stability. them to UIS. SiC devices have a the quality of the bond wire at- well with integrated ceramic Currently this test is done with 4H-SiC structure, which is com- tach. SiC MOSFETs are proving insulation. no gate bias but it is possible plex, and may be related to this to be almost as reliable as silicon in the future it will change observation. If this is not incorpo- devices. They have an odd charac- SiC Supply given that negative gate bias is rated into AEC-Q101, it still may teristic that is more pronounced While the power electronics Figure 2: MSC040SMA120B MOSFET passing 10K UIS hits at 100 mJ. generally used with SiC MOS- become part of a test for high than with silicon devices. Over industry had to deal with short- multiple kV range in the tens silicon devices and some unique FETs. reliability devices. the lifetime of the device there is term challenges of EPI substrate of amps. The high bandgap failure modes. The transportation • Temperature cycle (TC) test slight degradation of RDSon. This availability that affected both means they do not have the sector requires high reliability, and generates surface stress on a RUIS is common to all manufacturers silicon and SiC device lead times, high leakage like that of their the need for these high levels of device that can be a challenge Repetitive unclamped induc- at usually about 5 to 15 percent. SiC products are over this supply lower voltage silicon devices. reliability has been why engineers with some gate structures. tive switching (RUIS) testing is A design margin should be con- hump as additional substrate ven- • The body diode of SiC MOS- have been slow to accept SiC de- used to measure the stability of a sidering with RDSon if this is of dors are coming online and high FETs has a very fast recovery, vices. That’s now changing. Beyond AEC-Q101 device over time when placed in concern. In addition, this test has volume and mature SiC manufac- roughly an order of magnitude Eventually testing beyond the cur- a repetitive breakdown condition. shown that the device surface turing are in place to support the faster than that of silicon de- Automotive Standards rent AEC-Q101 may be required. Changes in MOSFET leakage and structure may influence the life- ramp in automotive adoption of vices. Automotive standard AEC-Q101 Microsemi has considered the threshold or changes in diode time. Vertical structure MOSFETs SiC solutions. • Due to the fast carrier recov- was developed around silicon following. leakage were common in the past. generally don’t do as well. ery SiC MOSFETs tolerate devices and provides a high perfor- With the proper substrate and Summary extremely high slew rates. It is mance standard for the automotive UIS good design practice this is no Rth The benefits of SiC solutions over virtually impossible to damage environment that removes some Unclamped inductive switching longer an issue. To gauge the lifetime expected silicon IGBT and super junction a SiC MOSFET by exceeding of the ambiguity in conventional (UIS) is a test where a device is from a device it is necessary to MOSFET-based solutions are its slew rate. commercial data sheets by guar- driven over voltage into break- Microsemi uses RUIS as part of a accurately measure the package evident at the system level for anteeing a level of testing to exact down. Most modern silicon test sequence to guarantee design thermal resistance. A SiC die is efficiency and reliability at high SiC solutions targeting the higher data sheet specifications. The AEC- devices can tolerate breakdown margin in the gate. Testing with typically small relative to the back power. Microsemi suggests going reliability of automotive applica- Q101 specification is relatively light energies on the order of Joules. our next-generation SiC MOSFETs metal in a discrete device. This re- beyond what is only auto-quali- tions do face some challenges. SiC on long-term reliability testing, Defects within individual devices has shown there is no degradation sults in a high heat flux localized fied, and this should resonate well is fundamentally a different crystal- and the need for long-term reliabil- make it necessary to test all de- of the gate or leakage after expo- under the die and the back metal with automotive engineers [1]. For line structure than silicon material. ity of SiC devices may introduce vices if a UIS rating is to be guar- sure to 10K RUIS pulses. Figure thermal interface presenting a more information on SiC solu- A SiC device of equal performance new qualification challenges. Also, anteed. This is not generally done, 2 shows a trigger, drain current higher thermal resistance than tions, please visit https://www.mi- has a much smaller die, allowing some of the tests required by AEC- which makes a UIS rating nice to and drain current in a 100mJ UIS would be expected than with a crosemi.com/product-directory/ more compact designs although Q101 may be more of a challenge have but not something to depend event. The drain potential on the calculation based upon the whole discretes/3613-silicon-carbide-sic. this introduces challenges with for SiC, which include: upon device to device. In this MSC040SM120 is 1.77KV during back metal area. This may be the heat flux density. SiC devices has respect SiC is the same. A properly breakdown. reason for high variability of the Microsemi some of the same failure modes as • High temperature gate bias designed SiC device can tolerate margin between the actual device www.microsemi.com

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to indicate the relative positions of the stator and the rotor to the Microcontrollers Evolve to controller, so that it can power the windings in the correct sequence Support BLDC Automotive Needs and at the correct time. There are also sensorless varieties which Small architecture changes early in the design phase impact power utilise back EMF to regulate the consumption of the end product motor. This more complicated setup, By: Spencer Manley, and Mathias Müller, Rutronik Figure 2: Packaging however, confers many advantages. Stepper motors – for incremental AC synchronous motors or DC The lack of brushes and physical s car manufacturers precision servomotors) are increasingly commutator means they do not strive to find ways Stepper motors are brushless being found in mechanically driven suffer the mechanical limitations to increase energy synchronous drives with at least applications with higher duty such as friction, electrical losses efficiency, and two phases that are controlled by cycles, such as power steering, fuel or worn out parts that are seen in Atherefore reduce CO2 emissions, PWM via half-bridges. In other pumps, transmission actuation brushed types, and means they the adoption of low-powered, words, these motors convert and engine cooling systems. can offer higher speeds, torque, low-weight electric motors for electric pulses into accurate and efficiency and life expectancy. auxiliary units - which work discrete 'steps' of mechanical shaft They are essentially an inside-out They also provide better heat separately from the main drive rotation. The amount of rotation configuration of a brushed DC dissipation and greater power motor - is on the increase. The produced by a stepper motor motor, with a rotor consisting of density in a smaller size and lower electrification of comfort and directly corresponds to the number an array of permanent magnets weight than brushed motors. As safety devices like fans and pumps of electric pulses it receives, while and a stationary armature they are virtually maintenance free, has also fuelled the demand for the motor's speed is proportional that is excited by an electronic they are also very suitable for areas standalone electric motors from to the frequency of the pulses. This commutation controller to likely to be contaminated with vehicle manufacturers. Highly means it can only take one step at produce torque. These motors are oil, grease and dirt as they can be integrated microcontrollers are Figure 1: PC Board a time and each step will be of the known as 'synchronous' because safely sealed away. being developed that support a the armature current if the stator and can create electromagnetic same size. the magnetic fields generated by wide range of these requirements. field is constant. interference. The current that the stator and the rotor revolve at Partly because of the cost erosion The various types of electric motor controls the motor is provided Because of the precise control the same frequency. of the more complex controllers, available offer different advantages This means for uni-directional to the windings on the rotor via offered by stepper motors, they BLDC motors are increasingly depending on how and where the purposes a simple transistor brushes (made of carbon), which, are often found in automotive While mechanically simple, BLDC becoming the electric motor of motor is being used. Here's a controlled by pulse width because they make contact with applications such as air control motors require sophisticated choice in automotive applications, quick refresher on the main types. modulation (PWM) is all that the rotating armature, will wear valves, headlight adjusters, control electronics and regulated ousting brushed types in all but is needed, while a half-bridge is down over time. This produces windscreen wiper controllers, power supplies. They are more the most niche areas. DC motors – direct control suitable for right/left rotation. a build-up of fine, electrically temperature gauges and fuel complex to control as the Brush-type DC motors are one of These motors are typically found conductive, carbon dust within gauges. controller must produce several Advanced BLDC controller with the simplest types of motors and in automotive applications with the motor that can create brush (usually three) alternating voltages embedded microcontroller provide precise control and easy comparatively short duty cycles, arcing. Also, they are not very well BLDC motors – highly durable whose frequency and voltage can The STSPIN32F0 Advanced regulation of speed and torque. like drives for adjusting seats and suited to high-torque applications The more complex but highly be adjusted and these always BLDC controller is perfect for The motor speed is approximately mirrors, or wash system pumps. as, when speed increases, brush durable Brushless DC motors need to be correctly in phase to those looking to benefit from proportional to the voltage Although inexpensive and generally friction increases and viable torque (which are also known as ensure the motor runs quietly the precise motion control and provided to the armature, while the reliable, brush-type DC motors decreases. DC commutatorless motors, and smoothly. Hall-effect sensors stable operation offered by BLDC torque produced is proportional to do require more maintenance electronically commutated motors, may be embedded in the stator motors. As one of ST’s System-in-

40 WWW.POWERSYSTEMSDESIGN.COM WWW.POWERSYSTEMSDESIGN.COM 41 SPECIAL REPORT : AUTOMOTIVE ELECTRONICS + INFOTAINMENT Holy Stone X7T

control to increase precision (also known as Field-Oriented Control Ceramic Capacitors or FOC) without the need for any additional components.

The MCU has 4KB of embedded SRAM which is accessed at CPU clock speed and has 32KB of non-volatile Flash memory for running programs and storing HCT Series: data. The unit also offers read and write protection modes for the Flash memory to protect against malicious hackers trying Superior Stability and to take control of the system. The MCU has 16 GPIO ports and is compatible with popular interfaces such as I2C, SPI, and Lower DC Bias vs X7R USART.

The STSPIN32F0 is a robust piece of kit, with an unusually wide operational temperature range starting at -40C and rising to +125C. To help protect ᮣ Voltage Ratings at 250V, 450V, and 630V against damage from over- Optimum heating it includes an embedded ᮣ Temperature Coefficient: +22%/–33%; overtemperature shut-down Capacitance at – 55° to +125°C protection that automatically ᮣ Capacitance Range: 0.01µF to 0.47µF restarts when temperatures come back into the safe range. Working Voltage ᮣ For applications such as LED Drivers, Figure 3: Block Diagram Power Adapters/USB Chargers, Lighting Package solutions, it combines a accept an operating voltage as The analog IC's integrated with Lower Ballasts, Telecommunication Equipment, three-phase BLDC electric motor low as 8V or as high as 45V, and comparator protects against over Power Supplies driver and an STM32 Cortex-M0 can output 3.3V when using a DC/ currents, and the threshold where Acoustic Noise ᮣ Available with Polymer Termination microcontroller (MCU), all DC buck converter, and 12V when this cuts out can be set by the and Arc-Prevention Coating for High housed in a tiny 7 x 7mm using an LDO linear regulator. MCU for special use scenarios. Voltage applications package. The power supplies also come Characteristics The embedded ARMv7 MCU with an under voltage lock-out Consisting of an analog and means there is no longer any protection to prevent low voltages a digital IC, the STSPIN32F0 need for an external processor, harming components on battery includes a three-phase gate driver reducing design complications, operated devices. with 600 mA current sink and costs and power needs. Its source, operational amplifiers, flexibility means engineers can Rutronik as well as a comparator. It can quickly use options like vector www.rutronik.com Holy Stone Enterprise Co., Ltd. Holy Stone (North America) International Holy Stone (Europe) Limited 41700 Ivy St., Suite D Henderson Business Centre, Unit 32 & 33 42 WWW.POWERSYSTEMSDESIGN.COM Murrieta, CA 92562 USA Ivy Road, Norwich, NR5 8BF, United Kingdom Tel: +1-951-696-4300 Fax: +1-951-696-4301 Tel: + 44-1603-251780 Fax: + 44-1603-251785 [email protected] www.holystonecaps.com [email protected] www.holystoneeurope.com FINALthought POWER SYSTEMS DESIGN DESIGN SPOTLIGHT Triad Magnetics WS Series Wall Plug-In Transformers Is Form Over Function a Take A Look Inside The WS Series MAGNETICS When compared to traditional 50-60Hz Triad’s WS Series Wall Plug-In Power power supplies, the WS Series is 25% more Choice for Computers? Supplies combine a state-of-the-art design, effi cient, 50% smaller and 70% lighter. superior performance and outstanding With its ROHS compliant surface mount components, the WS Series provides a clean By: Ally Winning, European Editor, PSD quality with excellent energy effi ciency to reduce power demand for a sustainable and compact lower density layout, which green friendly environment. is ideal for automated assembly and so pple is a company protection system quickly starts until now, none have handicapped reliable that they come with Triad’s superior that is not a stranger to throttle the processor speed, its products to the extent of 5-year warranty. to this column. The which in turn, brings the overall strangling the performance of Triad has designed custom wall plug-in company’s design performance of the laptop down its flagship computer, which power supplies for touchless faucets, Amethodology and choices are to a similar level to some of the is targetted at its heaviest and decorator lighting controls, motorized often market leading and deserve cheaper options available in the most loyal users. Do these users window shades that adjust all day long the praise they get. Then again, range. It’s a phenomenon suffered really care about shaving another following the sun and many more some of those design choices by most laptops at some point in millimetre off the casing, especially unique applications. tread the line between genius and time, when the cooling system just if it costs them a good deal of the Triad’s California Design Center madness, and over time, some can’t keep the processor to a safe performance they need. They meet or exceed the performance Triad’s innovative California design center decisions really have turned out operating temperature, but higher requirements of U.S. EISA 2007, California speeds your custom wall plug-in power to be genius and others to be cost computers are expected It also raises the question, how CEC and ECD 2005/32/EC, including Level VI supply, internal power supply, inductor or madness. One thing that has to suffer much less, and not as thin is too thin? Are we asking too energy effi ciency requirements. They’re also WS Design Typical Design transformer from design to prototype to available in an interchangeable package stood out about Apple products is regularly as the Apple top of the much from the designers of our testing to full production within weeks. that no matter the design choices range laptop does. electronic equipment? Laptops confi guration providing user versatility. The WS Series also features Class B EMI made, the performance of the have replaced desktop computers certifi cation with power isolation to fi lter product doesn’t suffer. That has With thinner laptops now in vogue, almost completely for most people out noise and provide common mode made the company’s computers throttling is becoming more and who use the computer as a work signal rejection. With safety pre-approvals, a favourite with people who have more common. It is annoying tool. As even some desktop tasks there’s no testing necessary. tasks, such as video processing enough when it happens on a become more demanding, should and 3D rendering, that need every cheap laptop, but when it happens we be asking for an option that Custom WS Plug-In Power Supplies ounce of power available. on a multi-thousand pound/euro is capable of performing the From a special output connector to a laptop that is specifically intended role adequately, or should we be unique case color, to a full blown custom Expert Engineering Staff That is until now. Apple’s latest to cope with almost any task flung happy to accept pencil thin cases, KEY SPECIFICATIONS design, Triad has the capability to provide With decades of expertise, the Triad design MacBook Pro range has been at it, it becomes all the more brushed aluminium and mediocre • Power: 6.75-36W a custom WS Series Wall Plug-In Power engineering staff works directly with you. found to throttle performance frustrating. In the past, Apple performance? • Input:100-240 VAC @ 50/60Hz Supply that will satisfy any requirement. They know the complexities of combining excessively because of the has made many of its most risky • Output: 4.5 to 24 VDC cores, laminations and bobbins into company’s drive to encase the choices with the company's laptop PSD • Typical six foot long cord custom power supplies and a wide variety electronics in smaller, thinner range, and many have paid off, but powersystemsdesign.com • Interchangeable input plug available of other magnetic components. form factors. This time, the main • Barrel connector output offender is the top of the range Triad engineers can suggest changes in choice, which features Intel’s APPLICATIONS design or materials to optimize your latest i9 processor. It appears that • Low voltage DC devices or circuits design. For some projects, long-life might be the most important thing. In other the small form factor of the case • Laptops, PCs, printers, phones You can change the output connector with a cases, materials changes can reduce costs. is not able to dissipate the heat • Audio, appliances, lighting & more production run of as few as 100 pieces. Triad generated by the processor and the can provide a custom case color for as few as 500 pieces. Triad can provide a complete For info or to purchase, go to: custom design with a minimum 1,000 piece www.TriadMagnetics.com order per year. 44 WWW.POWERSYSTEMSDESIGN.COM

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