psdemagapril2004 tocd (page 1)

CONTENTS

ViewpointEurope in the Spring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Industry News

Power Integrations Extends its Distributor Franchise . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

German Chapter Visits SEW-EURODRIVE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4

Philips and IMEC sign Agreement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4

Web-Based Tools for Design Performance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Free SPICE Modeling Service . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

eupec announces Chinese name to strengthen China ties . . . . . . . . . . . . . . . . . . . . . . . . .6

Cover Story

Visible Light Sensor Technology Pays Dividends . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12

Special Highlights

PCIM Conference Celebrates 25 Year Anniversary in Europe May 25th to 27th . . . . . . .29

Features

Technology Review—Power Management ? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Power Player—Digital Products Drive Power Management IC Growth . . . . . . . . . . . . . . .10

Alternative Power—Maritime Fuel Cell Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18

Sensors—Measure Both AC and DC High Level Currents . . . . . . . . . . . . . . . . . . . . . . . .23

Motor Drives—Stepper Driver for Automotive Appilications . . . . . . . . . . . . . . . . . . . . . . . .32

Power Management—Powering DDR Memory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .35

DC/DC Conversion—Power Supply Sequencing, a New Approach . . . . . . . . . . . . . . . . . .40

Power Semiconductors—Small Schottky with Big Potential . . . . . . . . . . . . . . . . . . . . . . .44

New Products . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .47-48

Member Representing

Eric Carroll ABB SwitzerlandBob Christy Allegro MicroSystemsPaul Löser Analog DevicesArnold Alderman AnagenesisDr. Uwe Knorr Ansoft Todd Hendrix Artesyn TechnologiesHeinz Rüedi CT-Concept TechnologyDr. Reinhold Bayerer eupecChris Rexer Fairchild SemiconductorAndreas Sperner IXYSDr. Leo Lorenz Infineon TechnologiesEric Lidow International RectifierDean Hendersen Intersil David Bell Linear TechnologyRüdiger Bürkel LEM ComponentsPaul Greenland National SemiconductorChristophe Basso On SemiconductorDr. Martin Schlecht SynQorDr. Thomas Stockmeier SemikronUwe Mengelkamp Texas InstrumentsPeter Sontheimer Tyco Electronics

Power Systems Design Europe Steering Committee Members

2 Power Systems Design Europe April 2004

To escape from the cold European climate,Spring days are starting to peek through theclouds back home in old Germany on the BalticSea. It is time to take out my old Beetle beingjust five years older than the PCIM Europeshow. Thinking about all the electronics in anautomobile today I am happy that we had engi-neers in the past able to design a car that canstay reliable over three decades. What is withtoday’s automobiles? Will we have semicon-ductor support 30 years into the future to pro-vide replacement and spare parts of all theelectronics in modern cars.

We have faced the same problem with thesteam engines in old locomotives or vessels.Here the permit for the usage of the steamengine is only given if the steam engine pass-es safety inspection. Different technology, samepattern. These products are now only for displayin the museums.

Does this happen to events as well. The bigopen air festivals are gone. Rosskilde Festivalin Danmark has attracted generations of Euro-peans including me. Did I get older and loseinterest, or is it that modern times take awaythese events. Things which become too com-mon lose the momentum to attract the people.

Major conferences and shows are only asstable if they have fresh blood coming in fromthe youngsters in engineering. We need indus-try to give younger engineers a start up chance.Revolutionary ideas are not developed by thegrandfathers. Their wisdom is a benchmark tomeasure progress for future developments.

The web is the complimentary tool today towork efficiently. Power Systems Design Europeis not only in print form but available digitally onthe web. This provides easy access to our mag-azine for world wide demand. Anyone, not justin Europe can get our magazine just by visiting

our web, www.powersystemsdesign.com. Wewill post all issues there and you will have thefreedom to travel and still get the news. Ourmagazine is a youngster in the publishing worldbut we are experienced oldies. Our averageage Jim and I (not Julia) is twice as old asPCIM Europe conference that will celebrate 25 years. PCIM started originally as a confer-ence and show in the US by Myron Miller. PCIMwas taken to Europe and organized by Gerd E. Zieroth.

Gerd’s words as a publisher in 1989 in PCIMEurope magazine are: “More than ever, indus-trial structuring and new trends in the field ofpower electronics, show clearly how neces-sary are the communications media, in order toprovide on a wide basis the right information, atthe right time, to the specialist user of this tech-nology throughout Europe. To this end, the“PCIM ‘89 Conference and the PCIM Europe”magazine combined their efforts.”

As a reminder, you should mark your calen-dar for the last week of May to attend the mostimportant European event in Power. My asso-ciation at PCIM Europe for more than one anda half decades as a board member of the PCIMconference will provide additional fuel for ourmagazine and keep the focus strongly set fortechnology and their advanced application. Seeyou at the podium discussions. Each dayaround lunchtime we will have short presenta-tions from experts followed by an open dis-cussion. I have selected semiconductors asthe focal elements for power electronics.MOSFETs on Tuesday, IGBTs on Wednesdayand Rectifiers on Thursday.

See you at the show in Nuremberg!

Best regards

Bodo [email protected]

Europe in the Spring

VIEWPOINT

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Volume 1, Issue 3

www.powersystemsdesign.com4 5Power Systems Design Europe April 2004

INDUSTRY NEWS

Power Integrations (NASDAQ: POWI),announced today that it has expanded its distributor network in Germany, Austria, andEastern Europe through Unique Memec, withwhom the company already has a successfulrelationship in Northern and Southern Europe.

“I am excited about the addition of UniqueMemec to meet the needs of our customersin Central Europe,” said Ben Sutherland,Managing Director of Power IntegrationsEurope, Ltd. “Unique Memec has made a

significant investment in switching powersupply application engineers and in equip-ping application labs over the last 18 months.Our ongoing strategy is to train the UniqueMemec field application engineers so theyare capable of assisting our customers todesign power supplies in their local language.”

“We have been successful selling solutionsusing the Power Integrations products andare looking forward to extending our cover-age to Germany, Austria and Eastern Europe.

We will offer the same high level of design-led expertise that our dedicated team ofpower FAEs around Europe already providesto our power supplier customers,” said JonEllis, European Marketing Director atUnique Memec.

Power Integrations Extends its Distributor Franchisewith Unique Memec

German Chapter Visits SEW-EURODRIVEIEEE Joint IAS/PELS/IES German Chapter

had kindly been invited by SEW-EURO-DRIVE to hold a chapter meeting in the pri-vate company’s headquarter at Bruchsal inGermany, which took place 4.-5. March 2004.After a warm welcome by owner and generalmanager Rainer Blickle, several technicalpresentations and a well organised tourthrough electronic and mechanical assemblylines permitted the 80 participants an impres-sive insight into technology, production andapplication specific final assembly of thecompany’s proprietary Eurodrives, which aredecentralised drives for various applicationsin industry and transportation. The technicalprogram was complemented by a scientificlecture of Prof. Dr. Budig about direct drives.

As an additional social program SEW gen-erously invited the participants to taste localfood and wine from amiable south-western

German region Baden in a wine cellar. Manydiscussions between researchers from indus-try and universities during the evening haveshown that the subject briefly addressed fromthe panel, how to develop the proven Germanengineering education in the European con-text with respect to internationalisation, actu-ally attracts considerable attention.

Presentation of structure and researchthemes of Nürnberg based EngineeringCenter for Power Electronics—ECPE—builtrelationship and further networking opportuni-ties with this newly founded organisation. The topic IEEE business has been used asplatform to review the three chapter meetingsof 2003, assigning awards for outstandingcontributions.

Picture: Recipients of chapter awards Dr.Miller (Infineon AG, left), Prof. Dr. ir. R. W. de Doncker (RWTH Aachen, with induction

motor trophy), Dr. H. Mitlehner (SiCEDGmbH), Dr.-Ing. T. Tolle (Philips Research)and Award Chairman Prof. Dr.-Ing. H. Späth(University of Karlsruhe, right)

More details can be found at:www.ewh.ieee.org/r8/germany/ias-pels.

Philips and IMEC sign AgreementPhilips Electronics

and IMEC signed anagreement that extendsPhilips’ access toIMEC’s advanced re-search facilities andexpertise until the endof 2008. This newagreement, whichclosely fol-lows Philips’

decision last year to become a core partnerin IMEC’s sub-45nm CMOS research program.

For leading consumer electronics compa-nies like Philips, having access to state-of-the-art semiconductor technology is the keyto delivering ever-richer experiences to con-sumers in areas such as multimedia enter-tainment and communications. However, in

addition to the baseline CMOS processesused to produce the powerful digital chips atthe heart of these ap-plications, companiesalso need special semiconductor processesto produce chips that can handle associatedtasks such as wireless communications,power amplification and display driving.Philips’ commitment to differentiating itself in the marketplace by providing total systemsolutions rather than component parts meansthat development of these special semi-con-ductor processes is as important to the com-pany as having state-of-the-art CMOS.Philips now works with IMEC on three levels–(i) as a core partner in IMEC's sub 45-nmCMOS research program and in JRP withIMEC on a 45 nm CMOS Research Program(in preparation for continued semiconductor

process development within the Phil-ips/Motorola/STMicroelectronics Crolles2Alliance); (ii) as an individual partner withIMEC in the development of Philips-specificspecial process technologies; and (iii) as avalued con-tributor to discussions over thefuture direction of semiconductor research at IMEC.

Further information on IMEC can be found on: www.imec.be.News from Philips is located at: www.semiconductors.philips.com

www.imec.be

www.ewh.ieee.org/r8/germany/ias-pels

www.powerint.com

www.semiconductors.philips.com

www.memec.com


Web-Based Tools for Design Performance

Fairchild Semiconductor announces theweb-based FETBench and Power FactorCorrection (PFC) Toolkit, allowing designersto dramatically shorten design times andspeed time to market. These online tools

offer choices of topologies, product selection,simulation creation, and many other features.The newly upgraded FETBench providescomprehensive MOSFET device selection,application analysis, and a new thermal simu-lation tool based on common power conver-sion schemes. A new design tool, the PFCToolkit, gives designers access to a powerfactor correction tutorial and selector mod-ules. Fairchild’s FETBench offers user inter-face and graphing tools, improved applicationsimulations, comprehensive thermal model-ing, and many new device models. Based ondevice behavioral models, provided byFairchild and user-selected parameters, thissimulation tool is able to graph accuratecurve tracer waveforms of input/output char-acteristics, such as ID vs. VGS, RDS(on) vs.ID, gate charge vs. VGS, RDS(on) vs. VGS,and others. The FETBench database utilizes

a library of over 300 Fairchild MOSFETdevices to recommend particular devicesbased on a selected application. Designershave access to customizable design opti-mization tools such as a curve tracer, dynam-ic characteristics test circuits, and circuit sim-ulations. Additionally, FETBench features adetailed thermal modeling tool, which is aninvaluable resource for designing applica-tions with stringent heat dissipation require-ments.

In addition to online design tools, Fairchildoffers archived webcasts and information tai-lored to facilitate designs for Computing,Consumer, Industrial, Ultra-portable andAutomotive applications.

Intusoft announced that its SPICE model-ing capability has been extended to users ofthe company’s ICAP/4 simulation software,and the overall engineering community, on a no-charge basis.

Intusoft has historically augmented its sim-ulation offering by providing a wealth of ana-log, digital, mixed signal and systems levelmodels to its software component library,now reaching 18,200 in part count, notincluding resistors and capacitors. It was the decision of Larry Meares, president andfounder of Intusoft, to now exclusively drive

new model additions directly from the engi-neering community. "This is the best way tocomply with today’s demand for SPICE mod-els, by respecting the needs of the engineer-ing tool user."

The modeling service directs an inquirer tofill our a Model Request Form, specifyingtheir company and contact information, and alink to the model’s datasheet, applicationnotes and test circuitry. For those not usingIntusoft’s simulation tools, the inquirer candownload a free version of the ICAP/4 analogand mixed-signal SPICE software and create

their own custom test circuit for the model.Tim Ghazaleh, marketing director for Intusoft,replied that the free modeling service isanother key way Intusoft is strengthening its relationship marketing program to its customer base and engineering community.The program forms a communication channelto Intusoft’s marketing organization, with cor-responding ties to the development team.

www.fairchildsemi.com

Free SPICE Modeling Service

www.intusoft.com

INDUSTRY NEWS

eupec displayed its advanced IGBT prod-ucts and High Voltage Diodes and Thyristorsat the PCIM exhibition in Shanghai. The IGBTproduct family enables the development ofnew concepts for motor drives in householdappliances, air conditioning systems, andindustrial applications. eupec is the only manufacturer of commercial Light TriggeredThyristors for HVDC and SVC markets.eupec semiconductors precisely and reliablyregulate energy flow in electrical products.

eupec leveraged the PCIM platform toannounce its new Chinese name. With aChinese name, eupec is strengthening itscommitment to develop China’s High PowerElectronics Industry. eupec plans collabora-tions with Premier Institutes in PowerElectronics, to update customers and

regional academia with latest information on products and technologies.

“A Chinese name brings us closer toChina, and demonstrates our commitment tostrengthening our investment and coopera-tion in the market,” said Mr. Erich Wallner,President of eupec. “China is a promisingmarket, as shown by our exciting results in2003. In the coming year, we will continue toprovide innovative products and solutions, as well as provide comprehensive support toour Chinese customers. We are confident wecan cooperate together with the China powermanagement community to supply the market.”

www.eupec.com

Power Events

• Hanover Industrial Fair, April 19-24,

Hanover, Germany

• Semicon Europe, April 20-22, Münich,

Germany

• PCIM 2004, May 25-27, Nuremberg,

Germany

• Fisita 2004, May 23-27, Barcelona, Spain

• Workshops, May 17-20, Power Supply

www.ridleyengineering.com

eupec announces Chinese name to strengthen China ties Features▼ Info & Online Store▼


TECHNOLOGY REVIEW

Modern controllers using C-MOSlogic run at extremely low volt-ages. You need to consider the

load and its conversion to obtain thecorrect voltage at the proper peak cur-rent. MOSFETS are the semiconductorelements that serve that purpose today.Any ICs helping here are named “PowerManagement IC”.

The most frequently asked questionis: what is low power and what is highpower? It depends upon the application.Individuals working on automotive con-trollers may define 42 volts as being ahigh voltage, high power. Conversely,those in Europe operating at 240 voltsor 420 volts, consider any value of volt-age below these values as low voltage.However, this voltage region is the mostcommonly used in industrial and com-mercial electronics.

The IC manufacturers are looking toapplications in communications, com-puter and the portable and wireless por-tion of that business. Here we have thestrong demand to use the give energy at the best performing efficiency. ICmakers like Lattice, TI and others play-ing here are using complex structures to have parts of the IC put to sleep whenthey are not needed and have algo-rithms to wake them up if they have tocontribute to the process.

All that takes place in the voltage rangebelow 5Volts as the controllers withincreasing clock cycle are moving to moredense structures and lower voltages.The challenging subject here, is theMOSFET working efficient in the lowvoltage arena.

The peak power demands are goingup and point of load converters are theones delivering the power right up to themicro-controller IC. Multi phase convert-ers are the tools to fulfill the support.

Based on what kind of volume appli-cation is in focus the semiconductormanufactures for the power manage-ment ICs and the discrete MOSFETs are working close with the Intel andAMD people to have the right solutionfor the motherboards of next generationcomputers. It does not matter if it isdesktop or laptop, both need optimizedsolutions as at the end the stand by timefor laptops is important if you are of thesupply. But also the heat is somethingthat needs to be extracted from the total design.

Worst case is the junction tempera-ture to be not exceeded the max junc-tion temperature before the device isdestroyed. Companies like Ansoft andIntusoft have design and simulation software to be ahead of hardware test to see how performance can be optimized.

Simulation has made a significantcontribution to system performance.Nowadays we have the product virtuallyready to go for production with veryclose to the final product. The more and more advanced software and theextraction of data from devices in semi-conductors and passives including thermal details prepares the platform to work straight ahead. The Simulationstarts on semiconductor design leveland goes step for step up and includesthe mechanics as well as the electricmotors to simulate total drive systems.Any thing in technology can be appliedfor simulation.

The computers of today have increasedcalculation speed together with “unlimitedmemory space”. Working with these toolstoday has much more detailed informa-tion to describe all elements more com-plex and have much more accuracy inthe model. That includes today thermalbehavior, something in the past thatneeded the engineers educated guessto feel if he was right or wrong. In a lotof cases the safety margin was too much.Or in some cases not enough and theactual device test showed the gaps.

So we have had our Eye on low andlower, now we take a look into automo-tive. In the sixties of last century theautomobiles got doubled their batteryvoltage to 12/16 volts until today.

We are now facing more electronics inthe car going to hybrid versions includ-ing complex engine management andhaving combined starter alternatordesigns coming. That means we arefacing a shift to the 36/42 volt board netin automobiles. All that is the main prop-erty of high density MOSFETs. below100 volts breakdown. Beside the aver-age car is delivered with so many elec-trical motors to move the windows upand down or position the seats that elec-tric power is the main thing in a car.

To convert between 12/16 volt and36/42 volt DCDC converters will beused. Even in most DCDC convertersSchottky diodes are not good enough insaturation voltage that more and morethe people learned that the synchronousrectification done by MOSFETs is thebest way to do it.

MOSFETs are today robust switcheswith a repetitive avalanche capability tomake them save in rough applicationslike Automotive with load dump condi-tions that need to withstand. Most of theadvanced MOSFETs have a very densestructure and use trench design. Thelow on resistance is now limited by thecontact technology in packaging. Herethe innovative steps are also importantfor power management.

The telecom bricks from the traditionalDCDC converter manufactures showedthe way how to do it. The algorithm todo it right and optimized is in the controland driver ICs driving the MOSFETs. Still watching the automobile we havethe IGBT as the switch in ignition atcombustion motors.

Don Burke, Fred Lokuta and I workedon the forefront last century to get it intothe automobile designs. Fairchild nowunderstands what they got from Harristo serve is very good for the market inautomotive. Here power managementjumps from electronically control to com-bustion efficiency, still power management.

Moving up in voltage gets us to theline voltage we have in Europe 240 ACas the US has 110 AC. Looking into thethree phase we are up at 420 volts in

Europe. Anyway we are in an areawhere the MOSFETs start to have problems solving the needs. The onresistance is the major drawback to fight against.

The right switch of choice at line voltage and frequencies from a fewhertz up to about 100Khz has becomethe IGBT. Introduced as the switch ofchoice for motion applications in 1982by Mr. Becke and Weathley from RCA.They called the device COMFET andgot the first IGBT patent from the USpatent office in December 1982. Sowhat, the IGBTs are the semiconductorswitches preferred when dealing withapplications requiring 600 to 1200 voltcapability. These areas are the house-hold equipment and industrial areas.Here we have a lot of applications going up to drive applications in the 2KW range handled by discrete IGBTs in a combined version with the free-wheeling diode.

Most popular applications are the variable speed electrical motor drives.To get them to the level of efficiency wesee today power management is thetool doing it. The inverter system is pow-ered from the supply voltages for thedriver circuits up to the bus voltage. Air-or magnetic bearings in the motor canbe part of the power management phi-losophy to reduce the waste of energy.

Above these power values, the appli-cations include power distribution at station class and traction. The preferredsolid-state device is the GTO andThyristor. Guess what is considered to be low voltage, low power in theseapplications? It depends upon your perspective! And again the “PowerManagement” is used as a terminologyhere. Regenerative breaking is a stan-dard in traction.

Will also become important in theautomobile by hybrid systems storingenergy while braking into supercapacitors or batteries.

We are covering in our Power SystemsDesign Magazine the entire gamut ofapplications in order to supply the power

designer with up to date crucial informa-tion that can help to facilitate the designbeing considered.

Power management is so wide inunderstanding and everyone sees it inhis own view like when the boss namedthe secretary a big white bird. What doyou believe their thoughts are? Shethinks about a wonderful swan and theboss thinks about a turkey both havetheir imagination to see things a differ-ent way. An old joke from my childhood.

www.irf.com

www.infineon.com

www.fairchildsemi.com

www.philips.com

www.ixys.net

www.advancedpower.com

www.stm.com

www.semikron.com

www.eupec.com

www.intersil.com

www.linear.com

www.maxim.com

www.powerint.com

www.renesas.com

www.hitachi-eu.com

www.meg.mee.com

www.microsemi.com

www.nsc.com

The definition is your position to look at

Power management starts at the device level with controller ICs that puts functions to sleep whennot needed or by slowing down clock cycles to save power. Followed by the distributed power

at the board or system level. Ending up in the high voltage at station class power generators and distribution.

By Bodo Arlt, Power Systems Design EuropeEditor-in-Chief

TECHNOLOGY REVIEW


POWER PLAYER

Many questioned our sanity 23years ago when we founded anew semiconductor company to

focus strictly on analog ICs. For this wasthe beginning of the digital revolution,and industry pundits claimed, “analog is dead.” Were they ever wrong.

In fact, growth in digital electronicshas created an even greater need foranalog ICs. Since our world is still ana-log in nature, conversion between theanalog world and digital processors willalways be needed. Today’s explosion infunctionality in portable electronic prod-ucts means even more analog ICs areneeded. Consider all the analog func-tions needed to support a modern cellu-lar phone with a color display, digital stillcamera, video camera and MP3 player.This growth in functionality also fuels theneed for an increasing number of powermanagement ICs.

Every new product generation seemsto require more power supply rails thanthe one before. Consequently, it’s nosurprise that power management ICsare one of the fastest growing segmentsin the analog IC industry. But there’smore going on than just increased useof regulators—we’re witnessing a dra-matic shift from simple linear regulatorsto more sophisticated switching regula-tors in nearly all applications. There areseveral key reasons for this movement.

The combination of reduced powersupply voltages and increasing load cur-rents makes linear regulators impracticalin many applications. Linear regulatorsoften generate considerable heat,

requiring significant PCB area and heatsinks. In battery-powered products,their inefficiency translates directly toreduced run-time. Just during the lastcouple years we have seen a dramaticshift from the use of linear regulators tovery tiny megahertz switching regulatorsin cellular phones in order to maximizebattery life.

Ten years ago Linear Technologyintroduced the first switching regulatorsfeaturing Burst Mode® operation to deliv-er excellent light-load efficiency. DC/DCconverters in handheld products nowconsume as little as 10uA quiescent current, increasing run-time in standbymode. Even in automotive applications,standby current is critical with over 100microcontrollers in a modern high-endcar. Unless each of these subsystemshas low standby current, the car batterymay be dead after parking just twoweeks at the airport. Modern high-volt-age switching regulators such as LinearTechnology’s LT1976 provide a break-through by consuming only 100µAduring standby.

Newer highly integrated switching regulators have become simple enoughfor analog-challenged designers to usesuccessfully. Some low-power switchingregulators require only three externalcomponents, making them almost as easyto use as the familiar linear regulator.

Looking ahead, we will continue inte-grating new features into switching regu-lators to improve performance and simpli-fy use. Several recently introduced prod-ucts incorporate spread spectrum switch-

ing to modulateswitching frequen-cy by a pseudo-random numbersequence. Insteadof concentratingswitching noiseinto narrow har-monics, noise isspread across the frequency spectrumto minimize interference with sensitivereceiver circuitry. Tracking and sequenc-ing features are also being integratedinto switching regulators to address theneeds of multi-supply systems.

The maturation of the power manage-ment IC industry has also resulted inapplication-specific parts for almostevery need. Linear Technology nowmanufactures over 3,000 standardpower management ICs, addressing awide range of general-purpose applica-tions, as well as very specific needssuch as multi-display white LED driversand Thermoelectric Cooler Controllers.Linear Technology will continue to leadthe power management IC industry bysetting new performance standards, and developing new architectures tomeet evolving system requirements. By maintaining close relationshipsbetween our design engineers and ourcustomers, we can better anticipateemerging product needs and help ourcustomers’ time-to-market with easy-to-use switching regulators.

For more information:+49 89 962 4550

By David B. Bell, President, Linear Technology Corporation

www.linear.com


COVER STORY

Power management in automatic brightnesscontrol applications

An Intel study on “Optimizing Mobile Power Delivery” reveals that display backlights represent33% of the total battery drain in notebook computers. Thus, finding ways to manage backlightbrightness—and the power consumed to achieve it—offers high potential for significant power

conservation. Automatic brightness control is one such solution.

By Bruce Ferguson, Sr. Systems Engineer, Microsemi Corporation

Our eyes may hardly notice a50% reduction in ambient light-ing, but if we control display

brightness and power consumption bythat same 50% we can provide a dra-matic impact on battery run time in anyportable device—and offer significantreductions in power consumption forstationary applications as well.

While many appliances include amanual capability for adjusting displaybrightness, few users employ it. Automaticcontrol of backlight brightness is there-fore essential to effective power man-agement in all types of display-baseddevices. It is also a critical factor forergonomic satisfaction, as displays areoften viewed under varying ambientlighting conditions.

Portable devices such as notebookcomputers and cell phones roambetween locations with vastly differentambient lighting—from daylight and

well-lit offices to the dimly lit cabin of aninternational flight. In automotive appli-cations, displays must operate over theentire visual brightness range from amoonless night to a sunny day. Evenwall-mounted LCD TVs must functionover a wide range of ambient lightingconditions in windowed rooms. Withoutautomatic brightness control, userseither strain to view washed out displaysin bright environments or over-illuminatetheir displays in dimmer light conditions.

What users need is a closed loop system that allows them to set displaybrightness to their personal comfortlevel once, and that will automaticallyadjust brightness thereafter as dictatedby changes in ambient light, optimizingthe display and conserving power.

A complicating factor concerning lightcontrol involves the necessity of ignoringthe effects of infrared light that is detect-ed by conventional light sensors, but not

by our eyes. Sunlight and incandescentlight have large concentrations of infraredcontent, as do some heat sources.

Beyond ergonomics, avoiding “over-bright” displays not only reduces powerconsumption, it also reduces stress onthe LEDs or CCFL lamps that illuminatethe display. Many LCD display specifica-tions show lamp life is improved by as much as three times, when the CCFLlamps are run at 50% of maximumbrightness; this translates into longerproduct lifetimes for notebook comput-ers, LCD monitors, and LCD TVs, wherethe lamps are not intended to be userreplaceable items.

Implementing Automatic BrightnessControl

In brightness control applications, twodesign parameters can be used to quan-tify the effect of ambient light that tendsto wash out information on a display.Eq.(1) below represents the Pixel


COVER STORY

Contrast Ratio (PCR)—essentially thebrightness of one pixel (typically fully on)divided by the brightness of anotherpixel (typically off). The PCR is more afunction of the display itself and howwell it minimizes unwanted reflections.The other is Display Brightness Ratio(DBR), which is the brightness of thedisplay relative to the surrounding ambi-ent. This can be a little more difficult toquantify for a portable device, because it depends on where you are using it.For the general case:

PCR = [T1x BL) + (R1 x A) / [(T2 x BL)+ (R2 x A)] (Equation 1)

T = Light transmittance of a pixel as determined by the liquid crystal drive

BL= Brightness of the LCD backlightR = Reflectivity of the display surface

at a pixel locationA = ambient light incident on the

display (illumination)

Equation (1) can be reduced to Eq.(2)as below.

BL= {[R1 (PCR x R2)] / [PCR x T2 – T1]} x A (Equation 2)

Since the goal of any brightness con-trol system is to keep the Pixel ContrastRatio (or PCR) constant for the user in avarying ambient, we can set PCR equalto a constant. The transmittance andreflectivity of the display can also beassumed constants for a given set ofdisplayed content. This allows equation2 to be reduced to:

BL = K x A (Equation 3)

This relationship clearly indicates thatPixel luminance or backlight brightnesscan and should be scaled directly tothe external ambient to maintain displayreadability. Assuming the pixel bright-ness is proportional to the dimming con-trol signal amplitude, this implies that asignal from a light sensor can be used to directly adjust the backlight controllerand provide automatic brightness controlthat keeps the display readable in allranges of ambient conditions.

Such an automatic brightness controlstrategy would also certainly improvedisplay readability in a hybrid system,where users manually select the initialdisplay PCR that satisfied their visualneeds, and the automatic brightnesscontrol system maintained that level with varying ambient lighting conditions.

Traditional light sensor technologyWith ergonomic factors clearly dictat-

ing that display brightness be automati-cally tailored to the ambient conditionsencountered by the user, the selectionof a light sensor to accurately detectambient conditions becomes the criticalfactor in implementing the control sys-tem. The most common light sensors inuse today are phototransistors and PINdiodes. Both types of sensor generatesignals that vary with incident ambientlight intensity, but each has significantdrawbacks in a number of brightnesscontrol applications.

The photodiode or PIN diode offers avery linear response to incident lightintensity, producing a current proportion-al to the ambient lighting. The outputcurrent from the photodiode is verysmall (typically nanoamps) so some sort of signal amplification is needed. Inaddition, the spectral response of a pho-todiode is most sensitive in the infraredarea so it typically requires the addition-al expense of an infared filter to ignorelight outside the visible spectrum(Figure1). In fact, contributions fromboth the infrared and ultraviolet regions

of the spectrum tend to increase thedetector signal far beyond the ambientlevel sensed by a user’s eye.

Phototransistors have a responsesimilar to a typical bipolar transistor with a photodiode driving the base. The transistor Beta provides the neces-sary current gain, which amplifies theweak signal of the photodiode input.Unfortunately, the transistor beta is not aparticularly stable parameter so the gainof the phototransistor circuit varies withsupply voltage, with temperature andwith manufacturing process tolerance;this means the phototransistor has limit-ed usefulness as a calibrated linear lightsensor and is not recommended forautomatic ambient tracking systems.

In many portable applications, design-ers have tended to accommodate ormask the broad spectral response ofPIN diodes in their brightness controlstrategies. But in several new brightnesscontrol application areas, like LCD TVsand automotive mirrors, response tolight outside the visible spectrum cancause severe performance problems.

For example, almost all remote controls for TVs use infrared signals to change channels or adjust volume.These signals can actually be sensed as incident ambient light by a light sen-sor controlling the TV display bright-ness, resulting in a significant change inbrightness of the TV screen without anapparent cause visible to the user.

Figure 1: PIN photodiode and Human Eye Spectral Response.

www.powersystemsdesign.com16 17

COVER STORY

Similar out-of-visible-spectrum illumi-nation effects have plagued the devel-opment of brightness controls for auto-motive mirrors and/or headlamps, whichare becoming increasingly necessarywith the use of new high intensity dis-charge head-lights and LED tail-lights.The sensitivity of commonly used sen-sors to the red area of the spectrum likethat emitted by tail lights can producefaulty control signals, dimming the mirrorreflectivity or lamp brightness at veryinconvenient times.

New integrated circuit visible light detectors

A new class of integrated circuit visi-ble light detectors is just emerging onthe market. These devices typically con-sist of an array of PIN diodes on a singlesubstrate, with individual diode charac-

teristics within the array controlled insuch a way as to match its overall spec-tral response very closely to that of thehuman eye (Figure 2).

With PIN diodes it’s possible to filterout the response to visible light. Whenthe response of an infrared sensitivePIN is subtracted from an otherwisematched full spectrum PIN, the result isa diode that is sensitive only to visiblelight. Using current mirrors, it is possibleto accurately amplify the PIN diode cur-rent by adjusting the physical size char-acteristics of the current mirror transis-tors (which is straightforward on an inte-grated circuit). This way, the good temperature coefficient and linearity of the PIN diode is reflected in the sensor output.

As an added benefit, the quiescentcurrent of these sensors is typically negligible and the devices are useful atextremely low light levels. When such adevice—like one of Microsemi’s LX1970family—is used with an appropriate con-troller for LEDs or CCFL, the signal fromthe sensor can be employed to directlycontrol display brightness for ambientvariations perceived by the human eye.

The LX1970 visible light sensor hastwo outputs that produce currents thatare proportional to the intensity of lightthat reaches the sensor. The SRC out-put is designed to source current into aresistor wired to ground. The SNK out-put is designed to sink current from aresistor wired to a high potential such asthe VCC. When only one output is used,the other output is left unconnected toreduce power consumption.

The value of the current source I-to-Vconversion resistor can be used to scalethe voltage produced at the LX1970output within limits. The upper limit isdetermined by the short circuit saturationcurrent of the LX1970, which occurs atapproximately 1000µA of output current;1000µA flows at approximately 2500 luxfor the LX1970. Attenuating the lightallowed to reach the sensor can extendthe upper range of the sensor at thesystem integration level. This can bedone using a gray filter or reducing theaperture of the hole in the cover abovethe light sensor to let in less light.

The lower limit is determined by thedark current of the device which for theLX1970 occurs around 1 lux. The supplyvoltage used will impose a maximumvoltage limit termed the compliance voltage of the LX1970 current source.The current source needs about 300mVof headroom. If a large resistor is used,the current source may run out of head-room and essentially clamp the outputvoltage such that further increases inlight have no effect; in this case, lower-ing the value of resistor can extend therange. Normally the output compliancevoltage is strategically used to limit themaximum output voltage since mostlight control systems have a peak bright-ness limitation that can be programmedin this way.

Power Systems Design Europe April 2004

Figure 2: LX1970 and Human Eye Spectral Responsiveness.

One precaution regarding the use ofthe visible light sensors like the LX1970is response time. Typically, the LX1970is much faster than the human eye.Most light sources produce light thatvaries considerably over a 60Hz cycleand the LX1970 can easily track this. To avoid this variation affecting sensitivedownstream circuitry, we recommendputting a capacitor across the resistor to set the time constant to around _ a second.

When the dimming control is donemanually, the user will normally changethe intensity of the LCD each time theroom ambient changes. With an auto-matic light control system, the usermakes an initial “one time” adjustment to their preference, and as the ambientlighting changes, the display brightnessadjusts to make the display appear tostay consistent at the same perceivedlevel. Figure 3 illustrates how a lightsensor control system can be designedto interact with user preferences to provide various brightness contoursover a limited range of ambient lighting conditions.

In Figure 3, it can be seen that at anyambient light level, with the LX1970 pre-scribed dimming control, the user canadjust the Dimming output from "off"(0% Duty) to an ambient specific maxi-mum level (100% Duty). Furthermore,for a given user adjustment level (orfixed PWM duty cycle), the Dimming signal will increase (decrease) as theambient light increases (decreases).The design parameters are the two corners on the maximum brightness setting contour: the percent full-scale at 0 lux, and the ambient level that produces a full-scale output. These twopoints will be programmed to give thedesired response.

The best approach to designing thebrightness control system is as follows:Determine the level of display brightnessdesired in total darkness (at full-scaledimming setting) and the light sourcedimming control voltage that correspondsto this display brightness. Design darklevel brightness control bias. Determinehow the sensor will be mounted and cre-ate a mockup to determine the sensorsensitivity in your application.

Determine the maximum level ofallowable display brightness and thecorresponding display dimming controlvoltage. Then determine the minimumlevel of ambient light where this maxi-mum level of brightness may be need-ed. Measure the light sensor output current using the mockup in this level of ambient.

For further assistance in calculatingresistor values, consult Microsemi forapplication information.

PWM Dimming Interface Conversion

The majority of applications for theLX1970 involve using it in conjunctionwith a lighting control system that isdimmed using a PWM signal from amicroprocessor; usually the resultantbrightness of the controlled light sourceis a function of the duty cycle of thePWM signal. In this type of system thelight sensor is best integrated by creatinga resultant dimming signal that is theproduct of the light sensor output multi-plied by the PWM duty cycle.

Typically there is a minimum level ofbrightness required in total darkness, so there is some control from the PWMsignal that must get through when thelight sensor output is zero (which would-n’t happen if they were truly a productfunction only). The circuit used to performthis function is illustrated below in Figure4. This circuit supports two modes ofoperation, an auto mode, which allowsthe user to adjust their brightness con-tour and works in conjunction with thelight sensor and a non-auto or manualdimming mode where the user directlycontrols dimming and the sensor influ-ence is removed.

Figure 3: User Interactive Dimming Control using LX1970.

4a) circuit before sensor

4b) new circuit with visible light sensor added

www.microsemi.com

Figure 4 : Adding a visible light sensor to a PWM dimming system.

COVER STORY


ALTERNATIVE POWER

These trends form the motivation todevelop new concepts in the fieldof energy conversion systems on

board ships. Although the performancerange for naval applications is very wide,i.e. from kW up to several MW, fuel cellshave the potential to meet these require-ments. The motivation mentioned aboveand the potential of fuel cell technologyresulted in several maritime fuel cellprojects. HDW already uses fuel cells asa series product on board submarines.On 20th March 2002, the first AIP (Air-Independent Propulsion) submarine waschristened at HDW in Kiel (Figure 1). Thefoundation of its subsidiary HDW - FuelCell Systems GmbH (HFCS) now givesthe HDW shipyard the opportunity touse its specific naval fuel cell knowledgefor fuel cell applications on surface ships.

Customer value for naval surfaceships

Today, the naval shipbuilding industryhas to face new demands.Environmental regulations are becomingstricter and comfort becomes more andmore important in order to win new cus-tomers. Naval ships are designed toreach the highest standards of stealthtechnology. The customer value is thedriving force to employ a new technolo-gy. The well-known specific properties

of fuel cells and fuel cell systems, suchas very low toxic emissions, low noiseand vibrations, modular design and high efficiency (especially with partial load)lead to a higher customer value forshipowners:

• very low toxic emissions• low fuel consumption • high comfort• low signatures• high resistance and combat strength

Performance of maritime applicationsThe performance ranges for fuel cell

systems used on board ships aredescribed in Table 1. Due to the highpower demand on board ships, the supply of individual consumers and/or asupport of the ship’s mains supply wouldbe a first realistic application. Since theperformance levels of fuel cell systems onhybrid submarines only range between200 and 400 kW, they are considerablylower than performance levels requiredfor surface ships.

Fuel cells on board commercial ships

In the maritime sector, environmental requirements are constantly increasing. In addition to that,increased comfort is required for passenger ships, while low signatures as well as increased

combat strength and resistance are essential for naval ships.

Stefan Krummrich, HDW-Fuel Cell Systems GmbH

Figure 1: Christening ceremony of the first AIP submarine at HDW in Kiel.

www.powersystemsdesign.com 2120 Power Systems Design Europe April 2004

Besides four fuel cell modules of 40kW each which are operated with hydro-gen the container also includes all theprocessing and electrical engineeringsystems for control and monitoring, aswell as an inverter which permits thegenerated electrical energy to be fedinto the ship’s mains. The electrical engi-neering systems have been designedflexibly so that it is possible to use theship’s mains in order to operate theplant with different voltages and line fre-quencies. It is also possible to operatethe container ashore and feed the ener-gy into the local mains network (e.g forport power supply).

Supply of fuel cells on board shipsThe generation of hydrogen and/or

the storage of a sufficient quantity ofhydrogen is one of the most importantchallenges for using fuel cells (especial-ly PEM) on board ships. Figure 4 showsthat in the case of a fuel cell plant oper-ated with hydrogen there is a fourfold(LH2) and/or tenfold (CGH2 350 bar)increase in the volume of the tank com-pared to conventional diesel fuels. Here,a storage in metal hydride cylinders isnot taken into account because of theweight and high costs. The low volumet-ric energy density of hydrogen and thehigh power demand on ships prevent a

wide-spread economic use of purehydrogen as energy carrier. Besides the problem of a large tank volume, thelack of a hydrogen infrastructure alsoimpedes the use of fuel cells on boardships, especially on commercial ships.The use of fuel cells on the basis ofhydrogen will therefore be reduced tolimited applications in naval engineering.Ferry line traffic, for instance, would be conceivable.

The diesel reformer represents onekey component for a wide-spread appli-

cation of fuel cell technology on boardships. It combines the advantages of thefuel cell with the advantages of the highvolumetric energy density of liquid dieselfuel. HFCS participates in various proj-ects which are developing reformercomponents at present.

The different stages of diesel reform-ing on the basis of steam reforming areshown in Figure 5.

It is necessary to desulphurize thediesel in order to protect the catalysts,included in the following process stages,and the fuel cell against damage.Sulphur-free fuels can be used alterna-tively. In the pre-reformer diesel is con-verted into methane and hydrogen. Thefollowing stages of the process, such assteam reformer, temperature shifts andselective oxidation are also contained inplants for the steam reforming of naturalgas. Alternatives to steam reforming areautothermal reforming or partial oxidation.

For applications on board ships thedevelopment of the components desul-phurization and pre-reformer is givenpriority since they are exclusively requiredfor reforming diesel. The development ofall other components is also carried outin other fields of application, e.g. resi-dential power generation and distributedcombined heat and power. Therefore, itis not necessary to develop an applica-tion for naval engineering only.

Figure 3: Model of the containerised 160 kWel fuel cell plant for maritime applications.

Figure 4: Storage volume for operating a FC plant of 300 kWel for 48 hrs (full load) in litres.

ALTERNATIVE POWER

Maritime fuel cell applications on submarines

After 20 years of development HDWtoday is able to commercially offer anair-independent propulsion for submarinesas a series product on the basis of PEMfuel cells. This includes the equipmentof new submarines as well as the retrofitof already existing submarines.

The most important advantages offuel cells on board submarines are:

• very high efficiency • silent energy generation process• lowest IR signatures• low maintenanceToday’s submarine plants consist of

the components described in Figure 2.

The Siemens FC modules are the heartof the fuel cell systems shown above.Hydrogen is stored on board the subma-rine in metal hydride cylinders, oxygenis carried in liquid form in tanks.

So far, 6 submarines of Class 212have been contracted. This type wasdeveloped in accordance with the

requirements of the German Navy.Besides the 4 submarines for theGerman Navy, Italy ordered 2 of theseboats which are built on the basis ofHDW documents at the Italian shipyardFincantieri. In addition to that, HDW hasdeveloped an export version with itsClass 214 submarine which has alreadybeen ordered by the navies of Greeceand South Korea.

Fuel cells on commercial shipsThe advantages of fuel cells on

commercial ships are clear: high fuel-saving potential, reduced toxic emis-sions, low operating costs, noiselessand clean propulsion.

In 1995, HDW together with Ballardalready investigated the use of fuel cellson board commercial ships incl. suitablefuels in a joint study. According to thisstudy, fuel cells are particularly suited for:

• emergency power supply• e.g. passenger ships, ferries• energy generation, in particular

environmentally friendly in highlypolluted ports

• e.g. container ships• energy generation / driving power

for ships with specific noise reduction requirements

• e.g. passenger ships, research vessels

• driving power on ships with hydro-gen or methane „boil off"

• e.g. LH2 carriers, LNG carriers

Fuels cells on naval surface vesselsIn the field of naval surface vessels

the investigations in Europe as well asin the US and Canada essentially focuson the “All electric ship” (AES). AES rep-resents a ship with integrated electricalenergy generation and a distributionsystem for propulsion, sensors, weaponsand general on-board electricity supply.The integrated all-electric propulsionsystem, however, is not likely to becomegenerally accepted on board frigatesand other large naval ships before thenext generation.

Apart from their advantages in thecommercial sector, in the naval sectorfuel cells are especially distinguished by:

• low signatures (acoustically, IR)• high resistance and combat strength

While in Europe and Canada primarilyPEMFC and Diesel reformers areplanned to be used as optional energygeneration units, US considerationsfocus on direct MCFC of Fuel Cell Energy.

Fuel cell plant for maritime applica-tions (FCMA)

In order to demonstrate the possibleapplications of the fuel cell technologyon board ships, HFCS is going to launchits own maritime fuel cell plant with apower output of 160 kWel soon. For this,existing Siemens fuel cells are convert-ed for the maritime application followingthe requirements of the classificationsocieties. Our partners are Siemens asfuel cell supplier and GermanischerLloyd for the safety-related conceptsand acceptance of the complete plant.

The FCMA has been integrated into a 20 ft. standard container so that it canbe installed easily on board ships. Figure3 shows a model of the plant.

Table 1: Performance ranges for ships.

Figure 2: Diagram of submarine fuel cell system.

ALTERNATIVE POWER


Our new current sensor “NCS”fullfills this requirement and isintended to be implemented

inside systems like UPS, windmills,welding, electrolysis, sub-stations... Up to now, the current sensor technolo-gy being used on this typical industrialor traction applications are listed below:

• Shunt with insulation conditioner,with the main disadvantage of heat dissipation, difficult installationand limitation on the over-currentmeasurement.

• Current transformer or Rogowskicoil, only working in AC condition,and requiring necessarily an integration function.

• Open loop or closed loop currentsensor, presenting limitation on over-current and immunity againstmagnetic perturbation.

Depending on customer applications,it is possible to use the NCS currentsensors in the place of each of this cur-rent measurement technologies, withthe main advantages of galvanic isola-tion, and wide continuous measuringrange without any over-heating.

Description of the technologyThe functioning principle is based on

the full application of the “Ampère’sTheorem” : the integration of the mag-

netic field vector on a closed contour(C) leads to the primary current I.

Figure 1.

In the air: ; the magneti-zation is proportional to the magneticfield, and there is no saturation level,eddy currents and hysteresis losses,

like it is with a magnetic core. On theother hand, the level of the primary current to be measured has to be highenough, in order to provide significantmagnetic field around the sensor.

We achieved the integration calcula-tion by using Hall effect probes thatpresent the advantage to be sensitiveeither to AC or DC magnetic fields (seeFigure 2).

The question is now to select the rightnumber of probes with the correct gainand with the convenient geometry, inorder to achieve the level of accuracybeing awaited by the customer application.

Many applications in the field of industry and traction markets need current sensors that are ableto measure both AC and DC high level currents (> 2 kA), with galvanic isolation and without

power and heat dissipation.

Georges Bustos, ABB Entrelec

Figure 2.

SENSORS

Current sensor implemented inside systems

Like in land-based distributed powersupply and in the mobile application fordriving busses and cars, fuel cells havebecome established in the operation ofvessels. On submarines, PEMFC oper-ated with hydrogen/oxygen are ready for production. At the same time, studiesand first demonstrations proved the rea-sonable use of fuel cells on board com-mercial and military surface vessels.

In order to demonstrate the fuel celltechnology on board ships, HFCS willlaunch a containerised 160 kWel fuelcell plant soon to operate it in variousmaritime projects. This will prove thebenefit of fuel cells. Furthermore, it willhelp to gain experience in different fieldsof application needed to develop a fuelcell plant that could meet the require-ments of a series production plant.

The use of pure hydrogen as energycarrier is only conceivable in particularcases because of the low volumetricenergy density of hydrogen and the highpower demand on board ships. Thediesel reformer represents one key com-ponent for the wide-spread applicationof fuel cell technology on board of ships.

HDW-Fuel Cell Systems GmbHStefan KrummrichWerftstr. 112-114D-24143 KielGermany Tel.: +49 431 700 – 4881Fax: +49 431 700 – 3586 email: [email protected]

http://www.industry.siemens.com/marine/en/products_systems/power_generation_fuel_cell.htm?PIdent=1003&SIdent=1191&TIdent=1193&QIdent=1199

www.hdw.de/hfcs

Figure 5: Diagram of a diesel reformer (steam reforming).

ALTERNATIVE POWER


On this purpose, we implemented a finite elements 3D simulation tool, which can calculate the distribution ofmagnetic field around each Hall effectprobe, and can provide the expectedlevel of accuracy of the complete current sensor.

The simulation tool is giving results in DC and AC conditions, taking intoaccount specific shapes of the primarybar and skin effect on the inrush current,with high level of magnetic perturbationaround the current sensor.

In a first step, we checked the rightcorrelation between simulation andexperiment results, in order to quantifythe level of accuracy of the simulationtool. Then we used the modelizationduring development phases.

Simulation toolThe following pictures give a compari-

son between simulation and experimentalresults on the global sensor accuracy, inAC and DC conditions, and give anoverview of the module of the magneticfield distribution around the primary bar.

The current sensor accuracy is meas-ured for different positions of the device,in a plane perpendicular to the transver-sal bar, for each 15 degrees position allaround the bar.

AC condition(Figure 4a and 4b).

In AC condition we can see concen-trations of magnetic field in some specif-ic area, due to the skin effect of theinrush curent.

It is very important to take into accountthis phenomenon, and to select the gainand the position of the probes in order toavoid any saturation that could affect theaccuracy level of the complete sensor.

High constraints ACIn all the cases that have been

considered, the maximum deviationbetween simulation and experimentalresults reached the expected goals.

Considering a finite elements mod-elization tool, this good accuracy levelcan be explained because all the phe-nomena are studying inside the air,which presents linear magnetizationcharacteristics, with no saturation properties to get in the way.

The simulation results analysing ledus to define the right number of probesand geometry, taking into account theworst environment conditions.

Thanks to this tool, we saved a lot oftime and avoided many prototypes andmeasurements realization. (Figures 5aand 5b).

Current sensorMechanical characteristics

The following picture gives themechanical description of the completecurrent sensor, with the different optionsof fixation.

This kind of modular fixation is possi-ble because of the low thickness andweight of this sensor that does not needany magnetic core inside.

The thickness of the product is onlydriven by the specifications on the gal-vanic insulation between primary andsecondary, and the leakage currents.(Figure 6).

Electrical characteristicsThe wide range of measurement is

the main particularity of this new currentsensor, with a continuously maximumcurrent Ipmax that can be five times the nominal current Ipn.

Furthermore, we provide as a standard,two different outputs: one dedicated tothe nominal current, the other one dedi-cated to the maximum current.

SENSORS SENSORS

Figure 4a.


Figure 4b.

Figure 3b.

Figure 3a.

DC condition(Figure 3a and 3b).

Figure 5a.

Figure 5b.

26

The most significantelectrical characteristicscorresponding to the“NCS125” sensor aresummarized in the table 1.

The current sensor isavailable with current andvoltage outputs. On the connector configurationversion, four outputs areavailable: 2 voltage out-puts (Ipn/Ipmax) and 2 currentoutputs (Ipn/Ipmax). 2 voltageoutputs or 2 current out-puts are available on thecable configuration version.As an example, we showbelow the corespondingconnection diagrams forthe current output version(see Figure 7).

PerformancesIn order to achieve a good level of

performance regarding the electromag-netic constraints and a good responseto the dynamic primary inrush current(di/dt), we implemented a specificlayout, disposition of components and floorplan.

Figure 8 gives the evolution of thesecondary response to dynamic primarycurrent with high magnetic disturbanceon the primary bar (see Figure 8).

The accuracy level that is achieved withthis new sensor is less than ±1% at thenominal primary current and ambianttemperature, and less than ±2 %, in any case.

ConclusionThis technology based on the absence

of magnetic core offers high savings involume and weight of the new currentsensor. Furthermore, this non-magneticproperty offers the possibility to with-stand continuously high level AC or DCcurrent with no dissipation.

SENSORS

Table 1.

Figure 7.


Figure 6.


On the other hand, the designerneeds to be very careful on the environ-ment application, in order to avoid lowerperformances of the current sensor dueto local saturation of Hall effect probes:shape of bars, working frequency, prox-imity of perturbation cables...

It is the reason why we developed, inthe same time, a modelization tool, as atechnical support to the design, avoidingthe realization of lots of prototypes andmeasurements.

The first applications available on the market will be the “NCS165” and“NCS125”, corresponding to an internalhole diameter of, respectivly 165 and125 mm; the primary nominal currentrange will span from 2 kA up to 30 kA.But this very compact new sensor willbe very useful for many other applica-tions needing high current and volume/weight savings. For example, it canreplace the entire function provided by a shunt and conditioner, in the ratingstargeted 2 to 30 kA, for the industry and the traction market.

This new technology has been patent-ed, regarding the electronic design andthe mechanical fixation mode.

ABB Entrelec / Control DevisionGeorges Bustos!0, rue Ampere, Z.I. - B.P. 11469685 Chassieu Cedex France

Figure 8.

www.abb.com

The Conference Directors Jean-Marie Peter, France, Prof. AlfredRufer, Prof. Helmut Knöll and

Prof. Johann W. Kolar and the organiz-ers are looking forward to welcoming allparticipants, many who have been com-ing for many years and those attendingfor the first time. The PCIM conferenceand show draws competent engineersand scientists from over 50 countries, all together like a family event andexchange their thoughts.

There are 4 key-note papers given byworldwide specialists, which will be heldeach morning open for all conferenceparticipants. Wednesday has two Key- Note Papers one right after theother. All together 187 papers are readyfor presentation. New this year, duringthe 3 day conference, participants willhave the opportunity to attend sessionsaddressing Power Electronics,Intelligent Motion and Power Quality.The whole event starts with tutorials onSunday. So don’t forget to review the

Professional Expert Training Courseswhich are offered on Sunday, May 23and Monday, May 24, before starting the three day PCIM conference.

It is a tradition to present new develop-ments in power electronic active andpassive devices, in power electronic circuits and applications, with high levelpresenters coming from academia andas well as from the electronics industry.PCIM is known as the internationalmeeting-point, to be the link betweendevice developers and device users, circuit and application designers offering

an original combination of conferenceand exhibition.

Prices and cost reductions drives indus-try, but other factors contribute: increasein performance, higher reliability, higherefficiency and other properties must addto the product attributes. And more andmore application fields, from generationto utilisation of electrical energy.

Experts from industry and academia will present the latest developmentsthey have worked on since our last conference and they will inform youabout future trends in advanced drivetechnology. The drive itself, rangingfrom low power stepper drives to largedrives in the megawatt range, has notyet reached the ultimate level of devel-opment. On the contrary, substantialimprovements in all application fieldscan be observed. Furthermore, sensor-less drives continue to represent a challenge to our colleagues in the devel-opment and application departments.

A quarter of a century of PCIM Europe conference and show will be celebrated in Nuremberg thisspring. Electronics has had the strongest influence in technology for the last century. The semi-

conductors switches have made a significant contribution to efficiency.

By Bodo Arlt, Power Systems Design Europe Editor-in-Chief

SENSORS SPECIAL HIGHLIGHTS

Power Electronics, Intelligent Motion andPower Quality


www.pcim.de

The field of Power Quality include manydifferent areas, from power levels, areasof applications, and technical conceptsand of major importance for customersthe delivery of reliable uninterruptiblepower supply. This falls into the special-ized process industry, telecommunica-tions companies and data centers

Be aware that the 8:30am opening ses-sion on Thursday in room Paris requiresearly arrival in Nuremberg. Right afterthat at 8:45am the first Keynote will beheld in room Paris. The Motor ControlTechnologies for the Hybrid ElectricVehicle—From the State of the Art toFuture Trends by Shoichi Sasaki,Project General Manager, Toyota Motor Corporation, Japan.

Mr Sasaki will give a brief introduction of hybrid systems, and their comparison,especially the system that is implement-ed in TOYOTA Prius, the first passengervehicle introduced in the world is pre-sented. And the motor control technolo-gies used in the Prius are also present-ed. Challenges for further developmentof hybrid vehicles especially on themotor and inverter are discussed.

Wednesday we have two key notesstarting at 8:30am with the first key note in room Paris. “A 40-MW, 60-kVElectric Drive System with a 70-km, sub sea DC Link—From the State of the Art to Future Trends” by Tom F.Nestli, Assistant Project Manager, ABB, Norway.

Mr Nestli will inform us about recentdevelopments within power electronicsand electric machines have enabled a40-MW, 60-kV transformer-less electricdrive system with the inverter and motorlocated in the North Sea, 70 km awayfrom the rectifier. This paper describesthis system and how it, along with othernovel power electronic solutions, takespart in forming the future of high powerelectronics applications.

At 9:10 am the second key note in roomParis has the following topic. “PowerIndustry Restructuring: Challenges onnew Technologies—From the State ofthe Art to Future Trends” by NouredineHadjsaid, Director of IDEA-GIE andProfessor at INP Grenoble, France.

Mr. Hadjsaid informs us about whatelectric power industry is experiencingtremendous changes and restructuringin the way it’s operated and plannedmore rapidly than at any time in its histo-ry. Privatization, open market and open-access, competition and customer ori-ented strategies are the keywords ofthis upheaval in many areas of theworld. As a result, electric power indus-try in its new environment is facing to arapid increase. The presentation willdeal with three main parts: The event of deregulation, some feedback experi-ences and potential development in new power electronics based equipmentin the context of restructuring of thepower industry.

Again at 8:30 am on Thursday the keynote will be held in room Paris with thefollowing topic. "Storage Technologiesfor enhanced Quality of Supply inConfigurations with Grid ConnectedRenewable Energy Sources—From the State of the Art to Future Trends" by Marion Perrin, Manager EuropeanProjects CEA Cadarache, France.

Mrs. Perrin tells us the news about thequality of supply is a point of growingimportance in the electricity networkswhile deregulation progresses on theEuropean market and electrical powergeneration becomes more and moredistributed. Grid connected storage systems are able to enhance the qualityof supply: by hindering blackout periods,by shifting the energy produced in excessfor use during high demand periods, orby sustaining the grid for better powerquality. In these different applications,diverse storage technologies areclaimed to be able to fulfil the technicalcriteria required.

So mark your calendar for the last weekof May to attend the most importantEuropean event in Power. My associa-tion of more than one and a half decadesas a board member of the PCIM confer-ence will provide additional fuel for ourmagazine and keep the focus stronglyset for technology and their advancedapplication. Handling podium discus-sions at PCIM 2004 in Nuremberg in theexhibition hall will allow you to stop byand make your comments. Each dayaround lunchtime we will have short presentations from experts followed byan open discussion. This time I chosesemiconductors as the focal elementsfor power electronics. MOSFETs onTuesday, IGBTs on Wednesday andRectifiers on Thursday will be the topic. I am looking forward to seeing you atthe podium. See you at the show in Nuremberg!

Come and select your personal sched-ule out of 187 presentations at theConference and Exhibition, or at thetechnical tutorials.

For details visit www.pcim.de

SPECIAL HIGHLIGHTS


MOTOR DRIVES

One of the major challenges forpower integrated circuits is inunder-hood automotive sys-

tems. These systems require semicon-ductors to drive the required power, pro-vide diagnostic and safety features andoperate under both temperature andvoltage extremes. One example of thisis the increased use of headlamp level-ling where a small stepper motor is usedto constantly maintain the level of thebeam. In addition, new features such asheadlamp steering are being introducedwhere a beam is made to follow thedirection of the vehicle to give increasedcornering visibility at night. To reduceEMC, the driving IC’s are increasinglybeing mounted close to the motorswhich means that they must be able tooperate with not only the heat from theengine but also the heat from the head-lamp pushing the ambient temperatureas high as 135C. Allegro MicroSystemshave brought together their extensiveexperience in stepper motor driverdesign, advanced BCD technology andthermally efficient packaging to producethe A3980, which has been specificallydeveloped for this type of application.

The A3980 provides a complete inter-face between a microcontroller or con-trol logic and a stepper motor. The con-trol circuit has only to provide a step anddirection input to operate a two-phase

bipolar stepper motor at up to 16microstep resolution. There are nophase sequence tables, high-frequencycontrol lines or complex interfaces toprogram. Microstepping gives theadvantage of lower noise and vibrationand helps to overcome the resonanceeffects that can stall a stepper motor atrelatively low step rates. The A3980integrates all the features to simply,accurately and safely control the currentin the two phase coils of a small bipolarstepper motor. It includes power drivers,pwm current control, D-to-A converters

and a translation table (see Figure 1).The integrated translator is an innova-tion from earlier products but new diagnostic circuits have been added to safely handle short circuits at themotor connections.

DMOS H-Bridge DriveThe power output to the motor is sup-

plied by two, all n-channel, low resist-ance, DMOS H-bridges. An integratedcharge pump, with an external capacitor,provides the gate drive voltage, higherthan the supply voltage, for the high-side n-channel FETS. The H-bridgeFETs are designed to maintain low on-resistance even down to 8V supply. Thephase currents through these H-bridgesis controlled by a fixed-off time currentregulator which can operate in fast orslow decay mode and can use synchro-nous rectification to reduce power dissi-pation (see Figure2).

Current ControlWhen using microstepping it is impor-

tant to maintain a uniform torque at allmicrostep positions. While this is some-what dependant on the motor character-istics, the phase currents must bestepped following a sinusoid, as shownin figure 2, so that the resultant torquefrom the two phase currents is as closeto 100% at all microstep positions. If the

Microstepping helps to overcome the resonance effects

DMOS FET drive, EasyStepper interface and tiny power package combine to simplify under-hood stepper motor control.

Bob Christie, Allegro MicroSystems

relationship between the phases isincorrect the microstep angle will beaffected and will cause motor vibrationand noise. In the A3980, a D-to-A con-verter that is designed and calibrated toproduce the required sinusoidal level at

each microstep generates the referencefor the current regulator. The result ofthis can be seen in Figures 3 and 4which show the relationship between the two phase currents for half and six-teenth stepping. In sixteenth step the

combination of the two currents producesa torque profile which is close to 100%at all microstep positions. The contribu-tion of the driver to the microstep posi-tion error is less than 2% of the full stepangle at any microstep position.

To further reduce noise and vibration,the decay mode is automatically select-ed based on the current at the nextmicrostep (Figure 2). When the currenthas risen from the previous step, slowdecay is used to minimise the currentripple in the motor winding. When thecurrent has fallen from the previousstep, fast decay can be used to counterthe effects of the motor back-emf, whichcan distort the current waveform.However, while fast decay helps with thephase current control, it will cause anincrease in the current ripple. This canbe reduced, and the current controlmaintained using a mixture of fast andslow decay. Initially fast decay is used toensure that the current is in control, thenslow decay is used for the remainder ofthe off-time to reduce the current ripple.The proportion of the off-time for whichfast decay is present can be adjusted foreach motor.

Protection and DiagnosticsTo improve system reliability, the

A3980 monitors all supply voltages andoperating temperature to provide under-and over-voltage lockout and thermalshutdown, and indicates any faults ontwo fault flag outputs. It also monitorsthe voltage across H-bridge FETs inorder to detect short circuits on the out-puts and take action to avoid excessiveheating or damage to the internal powerdrivers. As soon as a FET is turned onthe voltage across it should rapidly dropto a low value. The monitor circuit is dis-abled for a few microseconds after turn-on to ensure that capacitor charging cur-rents do not cause a false error. Afterthis short delay any power FET that issupplying excessive current, due to ashort circuit, will be turned off to avoiddamage. Even during the few microsec-onds when the FET is on it is possible toexperience currents in excess of eighttimes the normal operating current, seeFigure 5, which the power FETs must becapable of handling without damage.

Figure 1. The A3980 integrates all the features.

Figure 2. Resultant torque from the two phase currents.

MOTOR DRIVES

34 Power Systems Design Europe April 2004 www.powersystemsdesign.com 35

Since the A3980 is a power IC, pack-aging is another key element in a suc-cessful design. Although the thin small-outline package (TSSOP) is only 1.2mmhigh with a footprint of 10mm x 6mm it iscapable of dissipating over one Watt at125C when suitably mounted and willallow the A3980 to operate at up to500mA at an ambient temperature of135C. Thermal resistance from the heat generating area on the IC to theexposed thermal pad is only 0.5C/W.

When mounted on a 4 layer board with a ground plane heatsink area thethermal resistance to ambient can be as low as 25C/W.

Many of the design and packaginginnovations used in the A3980 havebeen applied to other recently releasedproducts including single H-bridgedrives for brush DC motors and relays,and a number of FET drive circuits forlarger brush-, and brushless DC motors.

All of these are focussed on the temper-ature and voltage requirements of auto-motive power control.

Bob ChristieEuropean Applications ManagerAllegro MicroSystems [email protected]

Figure 3. Sixteenth Step Figure 4. Half Step Figure 5. Short to ground behaviour

www.allegromicro.com

MOTOR DRIVES POWER MANAGEMENT

The speed enhancement over traditional SDRAM is the result oftransmitting data on both the posi-

tive and negative edges of the clock.Additionally, DDR SDRAM reduces deviceinput capacitance, reduces access timeuncertainty by using on-chip delay lockedloops, improves data capture reliabilityby adding data strobes and features anactive termination scheme called SSTL_2(Stub Series Termination Logic).

DDR use has provided increasedmemory speeds. DDR200 yields a 200-Mb/s rate with a 100-MHz clock.DDR333 is the next speed step in theDDR SDRAM products family that pro-vides a 333-Mb/s rate with a 167-MHzclock. DDR memory not only increasesthe memory bandwidth, but also reducesmemory power consumption. This is theresult of lower operating supply voltages(2.5 V vs. 3.3 V for SDRAM), lower volt-age swing associated with SSTL_2 logicand reduced time in active mode.

There are three voltages that need tobe generated and regulated in a DDRmemory system. In order to get the highspeed and keep the signal integrity, thebus impedance is controlled and termi-nated through a resistor to a midlevelvoltage called VTT. The signals are sin-gle-ended, but generated and compareddifferentially with respect to the mid-level

reference voltage VREF. VTT tracksVREF. VREF is bypassed to both theVDDQ and VSS ground plane using bal-anced decoupling capacitors. The othersupply associated with DDR SDRAM isVDDQ. This supply powers the DDRSDRAM I/O power, the clock synthesiz-er and the output drivers of the NorthBridge. In addition, VDDQ most likelysupplies the NB core, which still routine-ly operates at 2.5 V. DDR SDRAM offi-cially requires another supply for itscore, and this one is called VDD. Formost memories (i.e. Micron) the VDDhas the same specifications as VDDQand the two are externally connected as one.

DDR Power SystemAs illustrated in Figure 1, and dis-

cussed above, the DDR memory powersystem requires three voltage sources:

• VDDQ—provides the main power tothe memory

• VREF—low power reference sourcethat tracks the middle point ofVDDQ, and

• VTT—voltage source that powersthe parallel termination resistors.This third power source also has totrack the middle point of the VDDQvoltage, and be able to source andsink the termination current.

Desktop computers and datacomm systems

The majority of today’s desktop computers, along with many routers and switches, employ memory chips known as Double Data Rate Synchronous Dynamic Random Access Memory

(DDR SDRAM). DDR memory is appealing for hardware designers because it maintains the low cost SDRAM technology provides for main memory platforms while increasing

the effective data transfer rate.

By George Lakkas, Doug Mattingly; Intersil Corporation

Powering DDR Memory

Figure 1. DDR Memory Components on Motherboard.


POWER MANAGEMENT POWER MANAGEMENT

As mentioned, the power level of thereference voltage VREF is very low, inthe range of several mA, and is usuallyprovided by a buffered resistor divider.The other two required voltages, VDDQand VTT, can be provided by two inde-pendent synchronous buck convertersor a dual synchronous buck converter.Linear regulators can also be used at the expense of system efficiency and reliability.

Power Architectures for DDR MemoryThere are two main architectures for

powering VDDQ and VTT. One is toderive VDDQ and VTT independentlyfrom the input voltage source VDC, asshown in Figure 2a. The input voltagecan be a 3.3-V system bus, a 5-V sys-tem bus, or a 12-V system bus. InFigure 2b, the VDDQ and VTT buckconverters are cascaded which meansonly the VDDQ voltage is derived fromthe input voltage source VDC. The VTTvoltage is obtained from the VDDQ.

The advantages of the cascadedarchitecture are many. First, the VDDQconverter used in the independent archi-tecture has to be rated for current twotimes (2X) higher than that of the VDDQconverter in the cascaded architecture.In terms of component selection thismeans that MOSFETs with lower RDS(on) are required. Also, the output induc-tor must have bigger-gauge wire to beable to support the higher current. Inaddition, more filter capacitors arerequired. This results in higher Bill-Of-Material (BOM) costs.

The efficiency of the VTT converterthat boosts energy back to the primarysource while in sink mode is inverselyproportional to VDC2. This may notaffect the overall power system efficien-cy if VDC is 3.3 V to 5 V. However, at aVDC of 12 V, the efficiency decreasessignificantly. Also, the VDDQ minimumcurrent for the independent architecturemay go down to zero. The efficiency willsuffer in this mode (light load), becauseof the nature of the synchronous buckconverter.

The overall power consumed by a ter-mination circuit remains constant and is

strictly a function of the VTT voltage, thevalue of the resistors, and the number ofthe outputs being terminated as seen bythe following equation:

However, in the cascaded architec-ture, because of the lower input voltagefor the VTT converter (uses the VDDQas input), switching losses are severalorders of magnitude lower. The conduc-tion losses can be reduced by usingMOSFETs with lower RDS(on) without asignificant increase of the switchinglosses. Another benefit is that when theVTT voltage is derived from the VDDQvoltage, some protection features canbe simplified or completely omitted. Forexample, the Over-Voltage Protection(OVP) for the VTT output can be avoid-ed, because the drivers’ outputs arerated to the maximum VDDQ voltage.Similarly, the Over-Current Protection(OCP) for VTT can also be omitted,

because the OCP on the VDDQ sufficesas the termination resistors consumethe majority of the memory power.

Intersil’s DDR Memory PowerSolutions

Intersil was the first supplier of a highly integrated, fully compliant, dualDDR synchronous PWM buck controllerfor desktop applications. The IntersilEndura ISL6530, and ISL6531 providethe VDDQ, VTT, and VREF outputs froma single 24-pin SOIC or 32-pin 5 mm X5 mm Quad Flatpack No leads (QFN)package. These devices operate from a single 5-V supply and 5 V is the busvoltage used for power conversion. The VTT converter sources and sinksthe VTT load current. Figure 3 demon-strates the VTT current sinking loop. Anapplication circuit using the ISL6530 isshown in Figure 4.

Close relative to the ISL6530 is theISL6531. The ISL6531 differs from theISL6530 in that it has internal fixed gaincompensation for the VTT regulator.

Proper selection of the output inductorinsures stability and proper bandwidth.Figure 5 shows a typical DDR applica-tion using the ISL6531.

Both the ISL6530 and ISL6531 havemany features that make these powermanagement devices very suitable for desktop, workstation, and low-endserver DDR memory platforms. Both

controllers are 5-V input, single-supplydevices that provide all the requiredDDR voltages from a single package forreduced printed circuit board area. Eachhas a fixed 300KHz switching frequency,for simple design, and uses the upperVDDQ converter MOSFET RDS(on) as a free current sensing element. This technique eliminates a precisiondiscrete current sense resistor with itsassociated component and surfacemount placement costs.

The two PWM controllers switch out-of-phase, minimizing the input ripplecurrent and the number of output capac-itors. The devices also have a separateVREF_IN pin, that allows the user tooverride the internal resistor divider, andachieve output voltages other than thepre-selected VTT at 50% VDDQ.

The ISL6530 and ISL6531 also sup-port DDR system “S3” sleep modepower. The VTT is held at 50% VDDQvia a low-power window regulator toreduce power consumption and mini-mize wake-up time. Figure 6a shows the transition of VTT from active to sleepmode. This is accomplished by applyinga logic high signal to the V2_SD pin.Figure 6b shows VTT return from sleep mode.

Other features include: Power Goodfor system status monitoring, Shutdownfor protection, 0 to 100% duty cycle forfast DDR load transient response andan internal +0.8V Vref that makes these dual DDR regulators ideal forfuture DDRII memory systems. Figure7a shows the VTT regulator currentsourcing function during a VTT tran-sient. Figure 7b shows the VTTregulator current sinking function during a VTT transient.

The 32-pin 5x5 QFN package pro-vides the additional benefits of reducedDC/DC converter area and improvedthermal performance in comparison tothe 24-pin SOIC. The heat generatedfrom the switching of the on-boardMOSFET drivers is easily transferred to the PCB ground pad, onto which thecopper pad on the bottom of the QFN is soldered. The QFN picture and

Figure 2. Independent (a) and Cascaded Architectures (b).

(a) Independent Architecture

(b) Cascaded Architecture.

Figure 3. ISL6530 VTT current sinking loop.

Figure 4. ISL6530 Dual DDR Converter Application.


POWER MANAGEMENTPOWER MANAGEMENT

cross section in Figure 8 illustrate thisbenefit. The Intersil Technical Brief“TB389” on “PCB Land Pattern Design

and Surface Mount Guidelines for QFNPackages” can be downloaded fromIntersil’s Web Site for further details.

ISL6530 DDR Power ConverterLayout Considerations

Layout is very important in high frequency switching converter design.With power devices switching efficientlyat 300 kHz, the resulting current transi-tions from one device to another causevoltage spikes across the interconnect-ing impedances and parasitic circuitelements. These voltage spikes candegrade efficiency, radiate noise intothe circuit and lead to device over-volt-age stress. Careful component layoutand printed circuit board design mini-mizes the voltage spikes in the convert-ers. As an example, consider the turn-off transition of the PWM MOSFET.Prior to turn-off, the MOSFET is carry-ing the full load current. During turn-off,

current stops flowing in the MOSFETand is picked up by the lower MOSFET.Any parasitic inductance in the switchedcurrent path generates a large voltagespike during the switching interval.Careful component selection, tight lay-out of the critical components and shortbut wide traces, minimize the magnitudeof voltage spikes.

There are two sets of critical compo-nents in a DC-DC converter using theISL6530. The switching components arethe most critical because they switchlarge amounts of energy, and thereforetend to generate large amounts of noise.Next are the small signal componentsthat connect to sensitive nodes or sup-ply critical bypass current and signalcoupling.

A multi-layer printed circuit board isrecommended. Figure 9 shows the con-nections of the critical components inthe converter. Note that capacitors CINand COUT could each represent numer-

ous physical capacitors. Dedicate onesolid layer, usually a middle layer of thePC board, for a ground plane and makeall critical component ground connec-tions with vias to this layer. Dedicateanother solid layer as a power planeand break this plane into smaller islandsof common voltage levels. Keep themetal runs from the PHASE terminals to the output inductor short. The powerplane should support the input powerand output power nodes. Use copperfilled polygons on the top and bottomcircuit layers for the phase nodes. Usethe remaining printed circuit layers forsmall signal wiring. The wiring tracesfrom the GATE pins to the MOSFETgates should be kept short and wideenough to easily handle the 1A of drive current.

The switching components should be placed close to the ISL6530 first.Minimize the length of the connectionsbetween the input capacitors, CIN , andthe power switches by placing themnearby. Position both the ceramic andbulk input capacitors as close to the

upper MOSFET drain as possible. Place the output inductor and outputcapacitors between the upper MOSFETand lower diode and the load. The criti-cal small signal components include anybypass capacitors, feedback compo-nents, and compensation components.Position the bypass capacitor, CBP,close to the VCC pin with a via directlyto the ground plane. Place the PWMconverter compensation componentsclose to the FB and COMP pins. Thefeedback resistors for both regulatorsshould also be located as close as pos-sible to the relevant FB pin with vias tiedstraight to the ground plane as required.

DDR memory is becoming the main-stream memory in desktop and datacommunications systems due to itshigher-speed, lower-power consumptionbenefits and competitive pricing. Thechallenges it presents in terms of powersystem design can be more effectivelyaddressed using a cascaded buck dc/dcconverter, the practical benefits of whichinclude higher efficiency, lower totalsolution cost and reduced board space.This preferred architecture has beenimplemented in three of Intersil’s dualDDR PWM controllers: the ISL6530,ISL6531, and ISL6225. The ISL6530and ISL6531 provide a complete DDRmemory power system solution for desktop applications where 5V is thebus voltage.

Intersil CorporationMark E. HazenPublic Relations ManagerMail Stop: 53-200 2401 Palm Bay Road, NEPalm BayFL 32905USA

Figure 6. ISL6530 VTT Sleep Mode Transitions.

Figure 5. ISL6531 Dual DDR Converter Application.

(a) ISL6530 VTT ConverterSourcing Transient on VTT.

(b) ISL6530 VTT ConverterSinking Transient on VTT

Figure 7. VTT Source and Sinking Transients.

(a) ISL6530 VTT Converter SourcingTransient on VTT.

(b) ISL6530 VTT Converter SinkingTransient on VTT.

Figure 8. Quad Flatpack No leads (QFN) Package.


Figure 9. ISL6530 DDR controller layout recommendations.

www.intersil.com


DC/DC CONVERSION

This article looks at varioussequencing methods, highlightinghow a new generation of modular

point-of-load (POL) converters with built-in sequencing capabilities offers a par-ticularly cost-effective solution.

Silicon manufacturers are steadilyincreasing the performance and func-tionality of high-performance ICs bymoving to sub-micron fabrication. Thistrend is accompanied by ever-loweroperating voltages, to maximise switch-ing speeds and prevent secondarybreakdown of very small geometry tran-sistors. Consequently, virtually all highperformance ICs, including DSPs,ASICs, FPGAs and CPLDs, nowdemand several supply rails—one fortheir high-speed processing core, andone or more for their I/O functions.Typical core values are 1.2 V, 1.5 V or1.8 V, while I/O functions are usuallyhigher at 2.5 V, 3.3 V or 5 V.

Power sequencing is essentialTo avoid potential damage and latch-

up of the processing core, silicon manu-facturers strictly define the power-upand power-down sequence between theI/O and core voltage. However, satisfy-ing the sequencing requirements of alldevices on a card poses a considerabledesign challenge, because different IC

manufacturers recommend differentmethods. It can even get so complicatedthat the end application can have abearing on the sequence.

Designers mainly have a choice ofthree supply sequencing methods,known as sequential, ratiometric andsimultaneous. With sequential sequenc-ing, the rise of a primary supply controlsthe rise of secondary supplies, once asuitable delay period has elapsed.Ratiometric sequencing is a variant onthis, deriving a secondary supply controlsignal from a resistor divider on the pri-mary supply; it is principally only usedwith a few voltage regulator ICs and isconsequently not discussed in this arti-cle. Simultaneous sequencing allows allsupplies to begin rising together at thesame rate, until each supply reaches itsset point. This method offers the great-est opportunity for satisfying the differ-ent sequencing requirements stipulatedby different IC manufacturers, asdetailed later.

Sequential sequencing—variousapproaches

The simplest form of power sequenc-ing places an RC network between theprimary supply and the remote on/offcontrol input of the secondary powersource—typically an isolated or non-iso-

lated DC/DC converter or power regula-tor module. A major weakness of thismethod is that there is no way of guar-anteeing that later voltages will notcome up if an earlier voltage fails tocome up, so designers often include avoltage comparator and a voltage refer-ence to ensure that the first supply iswithin a proper voltage range before thesecond supply starts powering up, asshown in Figure 1. This process can berepeated on successive supplies.

The drawback to this method is thecomplexity of the additional circuitry thatis required, especially if it needs to shutdown in the reverse order to start-up.

Board designers can implement thistype of sequencing relatively easily –several specialist IC manufacturers pro-duce supervisory ICs incorporating suchcircuitry – but it occupies valuable boardspace, carries an additional cost over-head, and becomes unwieldy as thenumber of voltage supplies rises. Figure2 shows a typical circuit based on dis-crete components, using a supervisoryIC to monitor the outputs of threeDC/DC converter modules.

During power-up, once the superviso-ry IC determines that all three convert-ers have reached their nominal regula-

New generation of modular POL convertersMost cards designed for today’s communications and data processing applications demand a diversity of IC supply voltages. Correctly sequencing these supplies during power-up and power-down has long been a design issue, which is now being compounded by the stringent

demands of the latest ICs.

By Mark O’Sullivan, Artesyn Technologies

DC/DC CONVERSION

tion value, the voltage rails are appliedto the loads simultaneously. Thisapproach suffers from a high componentcount, and the designer has been forcedto include MOSFET power switches ineach supply path; these introduce loss-es, and can only handle relatively lowload currents.

Several semiconductor manufacturersalso produce fully-integrated sequencers,which are essentially microprocessorsthat control the sequencing of on-board

power sources and provide other powermanagement functions, such as moni-toring. Fully-integrated sequencers pro-vide a less cumbersome and moreaccurate sequencing approach than dis-crete RC-based implementations, andoffer considerable configuration flexibili-ty. However, they are invariably complexdevices that require programming, andfor many board designs represent anoverly sophisticated solution. Again,designers usually need to incorporatepower switches in the supply paths.

Board layout is complicated becauseseveral signal lines must be routedbetween the sequencer and each con-verter, limiting functionality, and thesequencers can be more expensivethan the converters they control.

This situation is set to change dramat-ically, following the introduction by anumber of manufacturers of a new gen-eration of POL converters that providebuilt-in power sequencing facilities andoffer current outputs from 6 to 30 A.

Auto-Track sequencing This new form of power sequencing is

unique to the PTH series of POL con-verters developed by Artesyn Technologies,Texas Instruments and Astec Powerunder the terms of the Point-of-LoadAlliance (POLA) initiative. Auto-Tracksimplifies the circuitry required to makeeach module power up and down insequence. The basic implementationfacilitates simultaneous sequencing;instead of successively delaying volt-ages, they are allowed to begin risingtogether at the same rate. Taking twovoltages—for core and I/O functions—as an example, both rise until the coresupply reaches its normal regulation(set-point) value; the higher I/O supplythen continues to rise until it too reachesits set-point value. During shutdown theexact opposite occurs.

Many board designers already usesimultaneous sequencing for dual-sup-ply applications. However, implementa-tion often proves difficult because one or more of the on-board power modulesmust be precisely controlled duringpower transitions. To achieve this withstandard commercial power supplymodules, the board designer needs toincorporate additional components andrequires detailed information about themodule’s output regulation circuitry—which is often not made available by the manufacturer.

The built-in Auto-Track sequencingcapabilities of all PTH series POLA-compatible power modules overcomethese issues by allowing their outputvoltage to be precisely controlled duringpower up and power down using only

Figure 1: Enhanced RC sequence circuit.

Figure 2: A typical power sequencing circuit based on an IC/discrete design

42 Power Systems Design Europe April 2004 43

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DC/DC CONVERSION

three external components. The controlsignal can be derived from a masterramp generator, the output voltage ofanother power module, or the module’sown internal ramp. Figure 3 shows atypical arrangement, using the modules’internal ramp facilities.

The operation of Auto-Track sequenc-ing is very simple. Every PTH seriespower module has an extra control pin,called Track. The output voltage of

each module precisely follows the volt-age applied to its Track pin, from 0 V toits set-point. Once the voltage on theTrack pin is raised above the module’sset-point, the output voltage remains atthis set-point.

A power-up sequence is initiated byapplying a logic high signal to the tran-sistor shown in Figure 3, pulling all theTrack pins to ground for about 10mstolet the modules complete soft-start

initialisation. During this time, the outputof all associated modules will be 0 V.After this period, the transistor can beturned off, allowing the track control volt-age to automatically rise towards themodules’ input voltage. Each module’soutput voltage will rise simultaneously,until it reaches its respective set-point,as shown in Figure 4.

Power-down is accomplished byreducing the track control voltage to 0V.The only constraints are that the powermodules must have a valid input voltageuntil the power-down sequence is com-pleted, and the track control voltagemust not fall faster than the Auto-Trackslew rate of 1 V/ms.

Artesyn has now launched 15 PTHseries non-isolated point-of-load DC/DCconverter modules, all featuring Auto-Track power sequencing and fully com-patible with POLA products from othermembers of the alliance. The modulescover a wide range of input/output volt-ages, and offer a choice of nine currentratings, from 6 A to 30 A. Electronicsdesigners can obtain these flexible low-voltage power modules from a variety of manufacturers, enabling them toimplement advanced power sequencingschemes for multi-rail boards very easilyand cost-effectively. Simply compare thecomponent count of the discrete circuitshown in Figure 2 with the Auto-Trackconfiguration shown in Figure 3 to gainan impression of the potential savingsoffered by this new approach to powersequencing.

Company contact:Jackie DayMarketing Communications ManagerArtesyn Technologies, Springfield Industrial EstateYoughal, Co. Cork, Ireland.Email: [email protected]

Figure 3: Typical circuit using Auto-Track sequencing.

Figure 4: Graph showing Vo1 and Vo2 vs. time when using the circuit in Figure 3.

www.artesyn.comSTAND #239

PCIM EUROPE—Nuremberg

May 25 - 27

STAND #239

PCIM EUROPE—Nuremberg

May 25 - 27


POWER SEMICONDUCTORS

components. International Rectifierdeveloped this approach to deliver thesmallest 1A Schottky diode in industry.As shown in Figure 1, the IR140CSPFlipKY utilises standard CSP technologyand revolutionises the low power marketby eliminating the lead frame and over-mold materials that are traditionally usedin low to medium power diodes.

Unlike previous silicon designs thatplace the anode and cathode on oppo-

site sides of the die, the 4 ball 1.5mm x1.5mm device provides anode and cath-ode connections on one side of the sili-con. With a total area of 2.25mm2 theFlipKY is 32% the size of the DO-216AApackage and is less than 14% of thesize of the ubiquitous SMA package(see Figure 2).

Making the anode and cathode con-nections directly through solder padsinstead of protruding leads not only

reduces the PCB footprint by 78% compared to the next smallest package,but also reduces the profile by 30% asshown in Figure 3. This enables theFlipKY to be designed into very tightspaces with very low height restrictions.The leadless connections allows design-ers to easily place the diode on a PCBexactly where it’s needed, further reduc-ing board level inductances and increas-ing the overall efficiency of the circuit.

This is particularly important if thedevice is being used as a freewheelingdiode in a synchronous buck converter.Any inductance between the switchnode and Schottky diode will delay thetime it takes for the Schottky to beginconducting. Delaying the conductionthrough the Schottky increases powerloss and thus reduces efficiency. Furthermore, if the inductance between theswitch node and the Schottky diode ishigh enough, the Schottky diode will not conduct at all.

As a true chip scale device, theFlipKY uses solder balls placed at a0.80mm pitch to allow conventional sur-face mount processes to be used. Themanufacturing process used to createthe solder balls, also known as bumps,is well known and widely documented

Figure 2: Package Size Comparisons.

Figure 1: FlipKY technology compared to existing package technology.

As consumer desire for smallerportable equipment with moreintegrated features such as built-

in cameras and internet capability oncell phones and personal data assis-tants (PDAs) grows, so is the demandfor smaller electronic components.According to a recent report from theCommunications Industry Researchers,the total market for Power ICs and asso-ciated discrete components used forpower management in mobile applica-tions will reach 4.3B USD in 2004 andclimb to 7.2B USD in 2008. In someinstances low power components canbe miniaturised by integration, but thereare still many power components suchas transistors and rectifiers that are noteasily integrated because of size limita-tions or the ability to sufficiently dissipateheat. Realising this, component manu-factures have been racing to reducepackage size and improve the perform-ance of devices that are not easily inte-grated into a single piece of silicon.

The race for component size reduc-tion began in the mid 80’s whenMotorola introduced the first surfacemount power package called the D-Pak.Until then, most three-pin power compo-nents were housed in larger lead framepackages, such as the TO-220 and thesmallest two-pin components were

housed in axial leaded devices, like theDO-204. Once surface-mount technolo-gy began gaining share in the transistormarket, diode manufactures beganapplying similar technologies to the two-pin devices. One of the first surfacemount rectifier packages to appear onthe market in the late 80’s was the D-64,which housed a 1A Schottky and had a15.4mm2 footprint. The next major sizereduction for a 1A Schottky came byway of the PowerMite (DO-216AA) inthe mid 90’s with about a 7.1mm_ foot-print. This was as considerable footprintreduction since there was hardly anyincremental improvement between thetime when the D-64 was released andthe DO-216AA was introduced to themarket. Since then there has been verylittle improvement in diode size reduc-tion while the value of board space con-tinues to increase with the demand formore functionality in portable products.

The problem with further size reduc-tion in power components such asdiodes is that in order to conduct a givenamount of current, a certain amount ofsilicon for a given technology is requiredto deliver desirable parametric charac-teristics and also efficiently dissipateheat. With traditional technologies, evenif the silicon area could be reduced sub-stantially and continue to meet paramet-ric requirements, the die would still needto be placed on a leadframe and thenover-molded to isolate the silicon fromenvironmental elements. Unfortunately,with existing processes the leadframeand over-mold volume typically exceedsthe silicon volume by a factor of wellover five. The additional volume requiredfor the surrounding package materialdramatically impacts the ability to fullyminimize board space and also intro-duces undesirable characteristics suchas increased thermal resistance fromjunction to ambient and lead inductance;not to mention assembly process stepsand cost.

Fortunately, there is a new approachthat combines existing silicon and chipscale packaging (CSP) technology todeliver Schottky diodes with the smallestfootprint and competitive parametriccharacteristics while minimizing theundesirable characteristics of packaged

A true chip scale deviceMaking the anode and cathode connections directly through solder pads instead of protruding

leads not only reduces the PCB footprint by 78% compared to the next smallest package, but also reduces the profile by 30%

John Lambert and Shawn O’Grady, International Rectifier



NEW PRODUCTS

Containing two highly sensitive mag-netic field sensors, the ZMX40M fromZetex can be used for accurately meas-uring linear position and high voltagecurrent. This magneto-resistive deviceprovides a measurement sensitivitymany times greater than that of tradi-tional Hall Effect devices.

Thin film permalloy stripes coveringeach sensor chip form a Wheatstonebridge providing an output voltage

proportional to the magnetic field (Hy)running the length of the SM8 package.Internal permanent magnets create aperpendicular field (Hx) that suppresseshysteresis and biases the sensors intheir linear region.

Mounted in parallel and separated byprecisely 3mm in the Y plane, the twosensors can accurately measure theposition of a magnetic object. A magnetmoving above the package stimulatesan output from each sensor that peaksas the magnet passes directly above.When the two peaks are of the sameamplitude, the magnet is exactly mid-way between the two chips.

With calibration to allow for tolerancedifferences between the sensor bridgeoutputs, the ZMX40M can resolve dis-tances down to 30µm in toothed wheelautomotive and machine tool applications.

By comparing the outputs and addingsome hysteresis, a large geometry mag-netic tape measure can be created.

By combining both bridge outputs andlocating an external current loop aboveor below the ZMX40M, a high voltagecurrent sensor can also be created. Sincethe current loop sits outside of the dualmagnetic field sensor package, com-plete galvanic isolation is assured.

Lin Collier, Zetex plc, Lansdowne Road, Chadderton, Oldham OL9 9TY,United Kingdom

Tel: +44 (0)161 622 4444Fax: +44 (0)161 622 4469E-mail: [email protected]

Dual Magnetic Field Sensor

www.zetex.com

throughout the industry. As shown in figure 4 the die is coated with siliconnitride passivation to protect it from theexternal environment. Only the areasthat define the solder bump positionsare left unpassivated. The under bumpmetallurgy is deposited here to preventthe die metallization from interactingwith the solder and to seal the passiva-tion, which prevents the ingression ofmoisture around the contacts.

The IR140CSP not only offers signifi-cant space saving compared to stan-dard leadframe devices, but also deliv-ers very attractive parametric character-istics. The device has an ultra-low 1AVF rating of 0.38V maximum at 125°Cproviding low power loss during conduc-tion, and a low leakage 25°C rating of80_A at 40V which helps to prolong battery life during non conductingcycles. Since the FlipKY does not have over-mold encapsulation, it has

the ability to dissipate heat directly intothe air making it thermally efficient.The thermal resistance from junction toambient (RTHJ-A) is rated at 62°C/Wmax. Additionally, because the four0.25mm balls make a direct solder connection from the die to PCB the thermal resistance from junction toboard (RTHJ-PCB) is also very efficientfor the footprint area and has a typicalvalue of 40°C/W when mounted on a 1"square PCB.

Typical applications for the IR140CSPinclude portable equipment, such as cellphones, PDA’s, laptop computers, handheld computers, MP3 players and harddisk drives where space savings andperformance are crucial to equipmentperformance.

Mike Wigg, International Rectifier Co Ltd, European Regional Centre439/445 Godstone Road,Whyteleafe, Surrey. CR3 0BLTel; +44 (0)20 8645 8003Fax; +44 (0)20 8645 8077e-mail: [email protected]

www.irf.com

Figure 4: Cross Sectional View of Solder Bump Interconnect.


Figure 3: Board FootprintComparisons.

Analog Devices extended itsVersaCOMM family of digital up-anddown-converters. Among the new products is the AD6633, a digital up-converter featuring breakthrough tech-nology that significantly reduces outputpower requirements for 3G wirelessbase station power amplifiers (PA). The AD6633’s innovative VersaCRESTcrest reduction engine enables optimumbaseband-to-IF (intermediate frequency)signal conversion by anticipating andreducing power peaks earlier in the sig-nal chain. Traditionally, base station

manufacturers have relied on expen-sive, highly linear power amplifiers toavoid output signal distortion caused bylarge peaking signals. Analog Devices'new solution reduces peak-to-averagepower by up to 6 dB, the equivalent ofreplacing a 40 W amplifier with a 10 Wamplifier. This means that manufactur-ers can either reduce their power ampli-fier expense while achieving dramaticpower savings of up to 75 percent, or,using the existing 40 W PA, an operatorcan support up to four times the cover-age area.

The AD6633 is Analog Devices’ firstdigital up-converter with crest factorreduction technology for CDMA2000, W-CDMA, and TD-SCDMA, 3G wirelesstransmitter applications. Operating at125 MSPS and processing four or sixchannels, the AD6633 is capable oftrading crest factor reduction againstsignal distortion. The signal distortionscan be allocated dynamically to any indi-vidual channel; thus, allowing operatorsto configure performance preferencesfor high quality data or lower qualityvoice communications. The converteralso features programmable widebandchannel filters that can be implementedfor CDMA2000, W-CDMA, or TD-SCDMAstandards, enabling manufacturers touse a single device across multiple platforms.

Analog Devices European Literature CentreC/o Harte-Hanks, Ekkelgaarden 63500 Hasselt, BelgiumFax: +32 11 300 635UK sales office: +44 1 932 26 60 00

VersaCREST technology reduces peak-to-average power by 6 dB

www.analog.com


NEW PRODUCTS

Companies in the issueCompany Page Company Page Company Page

ABB Entrelec . . . . . . . . . . . . . . . . . . . . .23Allegro MicroSystems . . . . . . . . . . . . .1,32Analog Devices . . . . . . . . . . . . . . . . . .1,47Anagenesis . . . . . . . . . . . . . . . . . . . . . . .1Ansoft . . . . . . . . . . . . . . . . . . . . . . . . . . .1Ansoft . . . . . . . . . . . . . . . . . . . . . . . . . .11Artesyn Technologies . . . . . . . . . . . . .1,40Bergquist . . . . . . . . . . . . . . . . . . . . . . .15CT-Concept Technology . . . . . . . . . . . . .1CT-Concept Technology . . . . . . . . . . .19Curamik Electronics . . . . . . . . . . . . . . .1Danfoss . . . . . . . . . . . . . . . . . . . . . . . .28eupec . . . . . . . . . . . . . . . . . . . . . . . . . .1,6eupec . . . . . . . . . . . . . . . . . . . . . . . . . .31Fairchild Semiconductor . . . . . . . . . .C2Fairchild Semiconductor . . . . . . . . . . . .1,6Fischer Elektronik . . . . . . . . . . . . . . . .46

Fuji Electric . . . . . . . . . . . . . . . . . . . . .27HDW-Fuel Cell Systems . . . . . . . . . . . .16IEEE . . . . . . . . . . . . . . . . . . . . . . . . . . . .4IXYS . . . . . . . . . . . . . . . . . . . . . . . . . . . .1Infineon Technologies . . . . . . . . . . . . . . .1International Rectifier . . . . . . . . . . . . . . .44International Rectifier . . . . . . . . . . . . .C4Intersil . . . . . . . . . . . . . . . . . . . . . . . . . . .5Intersil . . . . . . . . . . . . . . . . . . . . . . . . .1,35Intusoft . . . . . . . . . . . . . . . . . . . . . . . . . . .6LEM Components . . . . . . . . . . . . . . . . . .1LEM Components . . . . . . . . . . . . . . . . .3Linear Technology . . . . . . . . . . . . . . . . .7Linear Technology . . . . . . . . . . . . . . .1,10Mesago - PCIM Europe Nuremberg . . .29Mesago - PCIM Europe Nuremberg . .C3Microsemi . . . . . . . . . . . . . . . . . . . . . . .12

National Semiconductor . . . . . . . . . . . . .1NIC Components Corporation . . . . . . . .48On Semiconductor . . . . . . . . . . . . . . . . . .1Ohmite . . . . . . . . . . . . . . . . . . . . . . . . .22Philips . . . . . . . . . . . . . . . . . . . . . . . . . . .4Power Integrations . . . . . . . . . . . . . . . . . .4Power Systems Design Europe . . . . .22SynQor . . . . . . . . . . . . . . . . . . . . . . . . . .1Semikron . . . . . . . . . . . . . . . . . . . . . . . . .1Semikron . . . . . . . . . . . . . . . . . . . . . . .13Texas Instruments . . . . . . . . . . . . . . . . . .1Toshiba . . . . . . . . . . . . . . . . . . . . . . . . .48Tyco Electronics . . . . . . . . . . . . . . . . . . .1Tyco Electronics . . . . . . . . . . . . . . . . .34Zetex . . . . . . . . . . . . . . . . . . . . . . . . . . .47

Please note: Bold—companies advertising in this issue

Toshiba’s TB9060 controller IC forautomotive brushless DC motors combines sensorless operation withhardware-based PWM motor control.The result is a highly integrated solutionthat simplifies the design, reduces thesize, minimises the electrical noise, lowers the power consumption, andimproves the reliability of three-phaseDC brushless motors used in pumpsand other automotive applications.

By completely eliminating the need for

Hall sensor feedback, the TB9060 facili-tates the use of smaller motors and sim-plifies overall wiring requirements. Inaddition, removal of the need for Hallsensors ensures that information onmotor position is not adversely affectedby the electrical noise encountered inautomotive environments.

The TB9060 is a three-phase, fullwave sensorless brushless DC motorcontroller IC offering forward and reversemodes and capable of controlling outputvoltage from an external PWM input sig-nal. Two types of PWM output (upperPWM control and lower alternatingPWM control) and a lap turn-on functionfor smooth phase current switching con-tribute to reduced power consumptionand electrical noise.

The device offers configurable lead

angle settings of 0˚, 7.5˚, 15˚, and 30˚,allowing automotive designers to ensureoptimum efficiency depending on speedand load conditions.

The IC operates across the full auto-motive temperature. Built in protectionincludes an overcurrent function thatcan be used to switch the drive circuitoff when an abnormal motor current signal is detected.

Angela Fehrenbach, Toshiba Electronics EuropeHansaallee 181, D-40549 Düsseldorf,GermanyTel: +49 (0) 211 5296 254Mobile: +44 (0) 7712 791092E-mail: [email protected]

Brushless DC Motor Control IC for Automotive

www.toshiba-europe.com

Reduced case size NRE-WB alumini-um electrolytic capacitors from NICComponents Europe are ideal for use in electronic ballasts for fluorescentlighting and other high voltage applica-tions that require elevated temperature,extended load life performance.

The greater efficiency of fluorescentlighting—which is able to convertapproximately 25% of its energy to lightversus just 5% achieved by filamentlighting—coupled with an ongoing drivetowards greater efficiency, has created alarge and growing market for electronic

lighting ballasts.NRE-WB miniature radial leaded

devices have a high ripple current ratingof up to 2.0A (100kHz, +105∞C), andare available with capacitance valuesfrom 10mF to 220mF and voltage rat-ings of between 200VDC and 450VDC.Extended load-life of up to 10,000 hoursat high temperature makes NRE-WBcapacitors suitable for applicationswhere the replacement of worn compo-nents is difficult and cost prohibitive.

A wide operating temperature range of–25∞C to +105∞C enables the new

capacitor series to give stable, reliableperformance in applications where hightemperatures are present such as fluo-rescent lighting or in densely packedhigh voltage power supplies. Case sizesrange from 10mm x 20mm up to 18mmx 31.5mm depending upon rated voltageand capacitance value.

NIC response management is:NIC Components Europe Ltd., 14 Top Angel, Buckingham IndustrialPark, Buckingham, MK18 1TH, UK.

Electrolytic capacitors support high voltage applications

www.niccomp.com

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