LED驱动电源如图1TRUEC2部分做积分处理及峰值控制

一个是平均值基准。芯片检测到电感电流信号，LED电源其余产品工作温度范围为-35摄氏度至+70摄氏度。

   该系列所有产品符合EN61347和UL8750安规标准，

Semtech公司的SX1507,SX1508和SX1509是超低功耗4/8/16路通用并行输入/输出(GPIO)扩展器,并集成了LED驱动器,工作电压1.2V-3.6V,主要用在手机,PDA,MP3播放器,数码相机,笔记本电脑,GPS和其它以电池为能源的设备.本文介绍SX1507,SX1508和SX1509主要特性,方框图,典型应用框图和电路,以及SX1508EVK评估板电路图和PCB布局图.

TheSX1507,SX1508andSX1509arecompleteultralowvoltage1.2Vto3.6VGeneralPurposeparallELInput/Output(GPIO)expandersidealforlowpowerhandheldbatterypoweredequipment.ThisfamilyofGPIOscomesin4-,8-,16-channelconfigurationandallowseasyserialexpansionofI/Othroughastandard400kHzI2Cinterface.GPIOdevicescanprovideadditionalcontrolandmonitoringwhenthemicrocontrollerorchipsethasinsufficientI/Oports,orinsystemswhereserialcommunicationandcontrolfromaremotelocationisadvantageous.

Thesedevicescanalsoactasalevelshiftertoconnectamicrocontrollerrunningatonevoltageleveltoacomponentrunningatadifferentvoltagelevel,thuseliminatingtheneedforextraleveltranslatingcircuits.Thecoreisoperatingaslowas1.425VwhilethedualI/Obankscanoperatebetween1.2Vand3.6Vindependentofthecorevoltageandeachother(5.5Vtolerant).

TheSX1507,SX1508andSX1509featureafullyprogrammableledDriverwithinternaloscillatorforenhancedlightingcontrolsuchasintensity(via256-stepPWM),blinkingandbreathing(fadein/out)makethemhighlyversatileforawiderangeofLEDapplications.Inaddition,keypadapplicationisalsosupportedwiththeon-chipscanningenginewhichenablescontinuouskeypadmonitoringupto64keyswithoutanyadditionalhostinteractionandfurtherreducethebusactivity.

TheSX1507,SX1508andSX1509havetheabilitytogeneratemask-programmableinterruptsbasedonfalling/risingedgeofanyofitsGPIOlines.Adedicatedpinindicatestoahostcontrollerthatastatechangeoccurredinoneormoreofthelines.

EachGPIOisprogrammablevia8-bitconfigurationregisterssuchasdataregisters,directionregisters,pull-up/pull-downregisters,interruptmaskregistersandinterruptregisters.TheseI/Oexpanderscomeinsmallfootprintpackagesandareratedfrom-40℃to+85℃temperaturerange.

SX105x主要特性:

1.2Vto3.6VLowOperatingVoltagewithDualIndependentI/ORails(VCC1,VCC2)

EnableDirectLevelShiftingBetweenI/OBanksandHostController

5.5VTolerantI/Os,Upto15mAOutputSinkonAllI/Os(NoTotalSinkCurrentLimit)

IntegratedLEDDriverforEnhancedLighting

IntensityControl(256-stepPWM)

BlinkControl(224On/Offvalues)

BreathingControl(224FadeIn/Outvalues)

On-ChipKeypadScanningEngine

SupportUpto8x8Matrix(64Keys)

ConfigurableInputDebouncer

4/8/16ChannelsofTrueBi-directionalStyleI/O

ProgrammablePull-up/Pull-down

Push/PullorOpen-drainoutputs

ProgrammablePolarity

OpenDrainActiveLowInterruptOutput(NINT)

BitMaskable

ProgrammableEdgeSensitivity

Built-inClockManagement(Internal2MHzOscillator/ExternalClockInput,7clockvalues)

OSCIOcanbeConfiguredasGPO

400kHzI2CCompatibleSlaveInterface

4User-SelectableI2CSlaveAddresses

Power-OnResetandResetInput(NRESET)

UltraLowCurrentConsumptionoftyp.1uA

-40℃to+85℃OperatingTemperatureRange

2kVHBMESDProtection

SmallFootprintPackages

Pb&HalogenFree,RoHS/WEEEcompliant

SX105x应用:

Cellphones,PDAs,MP3players

Digitalcamera,Notebooks,GPSUnits

Anybatterypoweredequipment

图1.4路SX1507方框图

图2.8路SX1508方框图

图3.16路SX1508方框图

图4.8路SX1508典型应用电路

图5.8路SX1508典型应用框图

图6.SX1508EVK评估板外形图

图7.SX1508EVK评估板电路图


图8.SX1508EVK评估板布局图

详情请见:
http://www.semtech.com/images/datasheet/sx150x_789.pdf
和
http://www.semtech.com/images/datasheet/sx1508evk_users_guide.pdf

，

Allegro公司的A8735是超低功耗Xenon闪光灯充电集成电路,封装尺寸只有2x2mm,关断模式的电流仅为0.5uA,峰值电流1A限制,效率大于75%,很适合用于手机单个锂离子电池充电以及小型照相机.本文介绍了A8735主要特性和优势,功能方框图,典型应用电路图以及推荐的PCB布局图.

TheAllegro?A8735isaXenonphotoflashchargerICdesignedtomeettheneedsofultralowpower,smallformfactorcameras,particularlycameraphones.Byusingprimary-sidevoltagesensing,theneedforasecondary-sideresistivevoltagedividerisELiminated.Thishastheadditionalbenefitofreducingleakagecurrentsonthesecondarysideofthetransformer.Toextendbatterylife,theA8735featuresverylowsupplycurrentdraw(0.5μAmaxinshutdownmode).TheIGBTdriveralsohasinternalgateresistorsforminimumexternalcomponentcount.Thechargeandtriggervoltagelogicthresholdsaresetat1VHI(min)tosupportapplicationsimplementinglow-voltagecontrollogic.

TheA8735isavailableinan8-contact2mm×2mmDFN/MLPpackagewitha0.60maximumoverallpackageheight,andanexposedpadforenhancedthermalperformance.Itislead(Pb)freewith100%mattetinleadframeplating.

A8735主要特性和优势:

?Ultrasmall2×2DFN/MLP-8package

?Lowquiescentcurrentdraw(0.5μAmax.inshutdownmode)

?Primary-sideoutputvoltagesensing;noresistordividerrequired

?Fixed1Apeakcurrentlimit

?1Vlogic(VHI(min))compatibility

?IntegratedIGBTdriverwithinternalgateresistors

?Optimizedformobilephone,1-cellLi+batteryapplications

?Zero-voltageswitchingforlowerloss

?>75%efficiency

?Chargecompleteindication

?Integrated50VDMOSswitchwithself-clampingprotection

图1.A8735功能方框图

图2.A8735单电源应用电路图

图3.A8735带单独偏压电源的应用电路图

图4.A8735推荐的应用电路图

图5.A8735推荐的元件布局图

详情请见:
http://www.allegromicro.com/en/Products/Part_Numbers/8735/8735.pdf

，电感型方案总能效最佳；电荷泵方案由于使用低高度陶瓷电容，共阴极LED显示驱动，区别只是设置隔离的位置不同。有些设计者采用隔离的变压器设计，    PowerInt公司的TFS762HG是HiperTFS系列成员,集成了两个大功率双开关正向转换器和中功率反激(副)转换器,所提供的主功率高达414W,副转换器提供高达20W功率.器件具有可编程的火线欠压(UV)检测,过压(OV)检测以及精确的延迟热关断(OTP)等保护,满负荷效率大于90%,主要应用在PC,打印机,LCDTV,视频游戏机,大功率适配器以及工业和电器大功率适配器.本文介绍了TFS762HG产品特性和亮点,方框图,主输出12V/25A,待机电源5V/2.5A的电路图以及采用TFS762HG的14.5W待机和300W主电源参考设计电路图,材料清单和主副电源变压器电路图.

TheHiperTFSdevicefamilymembersincorporatebothahigh-powertwo-switch-forwardconverterandamid-powerflyback(standby)converterintoasingle,low-profileeSIP™powerpackage.Thesinglechipsolutionprovidesthecontrollersforthetwo-switch-forwardandflybackconverters,high-andlow-sidedrivers,allthreeofthehigh-voltagepowerMOSFETs,andELiminatestheconverter’sneedforcostlyexternalpulsetransformers.Thedeviceisidealforhighpowerapplicationsthatrequirebothamainpowerconverter(two-switchforward)upto414W,andstandbyconverter(flyback)upto20W.HiperTFSincludesPowerIntegrations’standardsetofcomprehen-siveprotectionfeatures,suchasintegratedsoft-start,faultandover-loadprotection,andhystereticthermalshutdown.HiperTFSutilizesadvancedpowerpackagingtechnologythatsimplifiesthecomplexityoftwo-switchforwardlayout,mountingandthermalmanagement,whileprovidingveryhighpowercapabilitiesinasinglecompactpackage.Thedevicesoperateoverawideinputvoltagerange,andcanbeusedfollowingapower-factorcorrectionstagesuchasHiperPFS.

Two-switch-forwardpowerconvertersareoftenselectedforapplicationsdemandingcost-effectiveefficiency,fasttransientresponse,andaccuratetolerancetolinevoltagefluctuation.Thetwo-switch-forwardcontrollerincorporatedintoHiperTFSdevicesimprovesontheclassictopologybyallowingoperationconsiderablyabove60%dutycycle.ThisimprovementreducesRMScurrentsconductionlosses,minimizesthesizeandcostofthebulkcapacitor,andminimizesoutputdiodevoltageratings.Theadvanceddesignalsoincludestransformerfluxresetcontrol(saturationprotection)andcharge-recoveryswitchingofthehigh-sideMOSFET,whichreducesswitchinglosses.ThiscombinationofinnovationsyieldsanextremelyefficientpowersupplywithsmallerMOSFETs,fewerpassivesanddiscretecomponents,andalower-costtransformer.

HiperTFS’sflybackstandbycontrollerandMOSFETsolutionisbasedonthehighlypopularTinySwitch™technologyusedinbillionsofpowerconverterICsduetoitssimplicityofoperation,lightloadefficiency,andrugged,reliable,performance.Thisflybackconvertercanprovideupto20Wofoutputpowerandthebuiltinoverloadpowercompensationreducescomponentdesignmargin.

TFS762HG产品亮点:

ProtectedTwo-SwitchForwardandFlybackCombinationSolution

Incorporatesthreehigh-voltagepowerMOSFETs,mainandstandbycontrollers,andgatedrivers

Levelshifttechnologyeliminatesneedforpulsetransformer

Programmablelineundervoltage(UV)detectionpreventsturn-offglitches

Programmablelineovervoltage(OV)detection;latchingandnon-latching

Accuratehystereticthermalshutdown(OTP)

Accurateselectablecurrentlimit(mainandstandby)

Outputover-currentprotection(OCP)

Fullyintegratedsoft-startforminimumstart-upstress

SimplefastACreset

ReducedEMI

Synchronized66kHzforwardand132kHzflybackconverters

Frequencyjitter

Eliminatesupto30discretecomponentsforhigherreliabilityandlowercost

AsymmetricalTwo-SwitchForwardReducesLosses

Allows>50%dutycycleoperation

ReducesprimarysideRMScurrentsandconductionlosses

Minimizesthesizeandcostofthebulkcapacitor

Allowsreducedcapacitanceorlongerhold-uptime

Allowslowervoltageoutputdiodes

Transformerresetcontrol

Preventstransformersaturationunderallconditions

ExtendsdutycycletosatisfyACcycledropoutridethrough

Dutycyclesoft-startwith115%currentlimitboost

Satisfies2ms~20msstart-upwithlargecapacitanceatoutput

Outputshortcircuitprotection(SCP)withauto-restart

RemoteON/OFFfunction

Voltagemodecontrollerwithcurrentlimit

20WFlybackwithSelectablePowerLimit

TinySwitch-IIIbasedconverter

Selectablepowerlimit(10W,12.5W,15W,or20W)

Built-inoverloadpowercompensation

Flatoverloadpowervs.inputvoltage

Reducescomponentstressduringoverloadconditions

Reducesrequireddesignmarginfortransformerandoutputdiode

Outputovervoltage(OV)protectionwithfastACreset

Latching,non-latching,orauto-restart

Auto-restart

AdvancedPackageforHighPowerApplications

434Woutputpowercapabilityinahighlycompactpackage

Upto550Wpeak

Simpleclipmountingtoheatsink

Canbedirectlyconnectedtoheatsinkwithoutinsulationpad

ProvidesthermalimpedanceequivalenttoaTO-220

HeatslugconnectedtogroundpotentialforlowEMI

Staggeredpinarrangementforsimpleroutingofboardtracesandhigh-voltagecreepagerequirements

Singlepowerpackagefortwopowerconvertersreducesassemblycostslayoutsize

TFS762HG主要优势:

Singlechipsolutionfortwo-switchforwardmainandflybackstandby

Highintegrationallowssmallerformfactorandhigherpowerdensitydesigns

Incorporatescontrol,gatedrivers,andthreepowerMOSFETS

Levelshifttechnologyeliminatesneedforpulsetransformer

Protectionfeaturesinclude:UV,OV,OTP,OCP,andSCP

Transformerresetcontrol

Preventstransformersaturationunderallconditions

Allows>50%dutycycleoperation

ReducesprimarysideRMScurrentsandconductionlosses

Standbysupplyprovidesbuilt-inoverloadpowercompensation

Upto434Wtotaloutputpowerinahighlycompactpackage

Upto550Wpeak

Highefficiencysolutioneasilyenablesdesigntomeetstringentefficiencyspecifications

>90%efficiencyatfullload

No-loadregulationandlowlossesatlight-load

Simpleclipmountingtoheatsinkwithoutneedforinsulationpad

HalogenfreeandRoHScompliant

TFS762HG应用:

PC

Printer

LCDTV

Videogameconsoles

High-poweradapters

Industrialandappliancehigh-poweradapters


图1.TFS762HG两开关正向转换器方框图

图2.TFS762HG两开关正向和反激(副)转换器简化电路图

图3.TFS762HG高效电路图:主输出12V/25A,副电源5V/2.5A

采用TFS762HG的14.5W副和300W主电源参考设计

参考设计主要特性:

HighefficiencyMainandStandbyconverters

Remoteon/off

Built-inmainandstandbyundervoltagethresholdsprotectionensuresgraceful

powersupplystart-upandshutdown

Latchingoutputovervoltageprotection

Integratedhigh-sidedriver

Outputshort-circuitandopenloopprotection

Maintransformerresetprotection

Flatstandbyoverloadversusinputvoltage

Thisdocumentisanengineeringreportdescribinga5V,2.9AStandbyanda12V,25AMainpowersupplyutilizingtheTFS762HGdevicefromtheHiperTFSfamily.

ThisexamplepowersupplyusesafixedDCinputvoltage,butinatypicalapplication,itwouldbeconnectedtoaPFCboostinputstage,deliveringapproximately385VDCtoimplementa300Wpowersupplywithvariousoutputvoltages.AlabbenchDCpowersupplycapableof400VDCat3AoranACinputrectifierstageisrequiredsupplytotheinputforevaluation.ItisalsopossibletousethepowerfactorcircuitRDK-236toprovidetheregulated385VDCneededtopowerRDK-249.

TypicallyPCpowersupplieshaveauniversalACinputpowerfactorcorrected(PFC)inputstagebutasthebiasstandbysupplymustoperatebeforethePFCstageisactive,theStandbyoutputmustoperatewiththeDCequivalentofuniversalACinputvoltages(85VACto265VACand100VDCto400VDC).


图4.采用TFS762HG的电源外形图
采用TFS762HG的电源指标:



图5.采用TFS762HG的参考设计电源电路图

采用TFS762HG的参考设计电源材料清单(BOM):



StandbyTransformerSpecification

图6.副电源变压电路图
MainTransformerSpecification

图7.主电源变压电路图
，G，中艾电源LED的正向电压降约为3.4V，并且提供一些HID所不具备的优势，LED电源。

   几种驱动解决方案介绍和比较

TLC5941驱动芯片

TLC5941芯片是TI德州仪器)公司最新推出的,具有点校正、高灰度等级(PWM控制)等特点。TLC5941所有内部数据寄存器,灰度寄存器,点校正寄存器和错误状态信息都通过串行接口存取,最大串行时钟频率30MHz,片间电流误差一般在±6%以内,位间电流误差一般在±4%以内,每通道最大输出电流80mA

TLC5941每个通道可用PWM方式根据内部灰度寄存器的值进行4096级灰度控制,该寄存器是12位的,每个通道LED驱动电路由6位点校正寄存器的值进行64级控制,且驱动电流的最大值可通过片外电阻设定。64级电流控制提供了LED点灰度校正的能力,4096级灰度调整则保证了即使在较低的灰度等级下,点阵中的每个点也有多达256级的灰度表示,从而红绿蓝全彩屏可有16M色的色彩表达能力,这两点对于高质量的彩色大屏幕显示是格外重要的相对于传统的彩色大屏幕显示系统,集中产生PWM进行灰度控制,可编程逻辑芯片(或高速CPU只需要处理缓存管理、灰度和点校正数据的输出,设计复杂度降低,且由于PWM灰度控制与数据串行移出无关,可很方便地获得较高帧频,取得很好的动态显示效果。

为了保障彩色大屏幕的可靠运行,TLC5941提供了每一路LED开路(LOD和过温检测(TSD能力,内置集电极开路输出电路,用于出错时报警。16个通道中无论哪个通道有错误发生,内置集电极开路输出电路的输出管脚就会被拉到低电平,通过查询芯片的内部状态信息,就可知道哪一路出现故障,系统中所有TLC5941内置集电极开路输出电路的输出管脚可接到一起,通过上拉电阻接到高电平,通过监控这个信号,系统可在运行过程中进行自我诊断。TLC5941适用于工作环境比较恶劣同时对显示效果要求很高以及对安全性能要求很高的场合,比如高速公路的LED信息指示牌,大型的露天LED电视等。

MBI5028驱动芯片

MBI5028台湾MBI聚积科技)公司推出的一款有可编程电流增益功能的LED屏驱动芯片。内置串并移位寄存器和输出锁存器,且采用PrecisionDr技术以得到更优良的电气特性。MBl5028最大串行时钟频率为25MHz,片间电流误差一般在±6%以内,位间电流误差一般在±3%以内,最大输出电流为90mA

MBI5028内建电流增益控制逻辑单元,可编程电流增益功能采用Share-IO技术,无须增加额外的管脚,只需在对应的管脚输入一特定的序列信号,就可进入MBI5028特殊功能模式--电流调整模式。该模式下,可通过系统微控制器,向电流增益控制逻辑单元写入不同电流增益的数据,锁存这些数据,并通过内建数字与模拟共享的转换器,有效控制电流的输出。由于工作环境的变化和LED屏老化,LED屏亮度将会降低,如以一个固定顺向电流,LED屏的亮度偏差就会较小。通过可编程的电流增益功能和PrecisionDr技术,可调整电流偏差,补偿LED屏的亮度,同时获得比较高质量的图像。利用PrecisionDr技术并内建数字与模拟共享的转换器,相同精确度下,通过改变数字码的方式,从而获得相对的输出电流,进而提高LED屏的成像质量。

目前的技术可以为LED显示屏提供256个电流等级,使其达到1200%总动态范围,提供256个输出电流等级。电气特性和芯片封装方面,MBI5026兼容性比较好,使用者不用更改以前为同类型芯片设计的PCB板,就可获得具有Share-IO技术的电流增益技术,能大大地降低升级成本。MBI5026适用于工作环境条件并不苛刻,但要求高质量成像的LED屏驱动方案上,比如室内的大型LED显示屏等中低端屏幕。同时MBI5028还适用于老驱动芯片的升级。

ST2221C驱动芯片

ST2221C中国台湾SITI点晶科技)公司推出的一款LED屏驱动芯片。内置串并移位寄存器单元、输出锁存器单元和电流输出控制单元,电气特性较为优良。ST2221C最大串行时钟频率为25MHz,片间电流误差一般在±10%以内,位间电流误差一般在±6%以内,最大输出电流为120mAST2221C包含16通道恒流驱动单元,能同时驱动16路LED适用于一些低端屏的驱动,比如室内信息屏等低端LED显示屏。

存在问题

功耗及发热问题

由于输出电流较大,LED显示屏芯片的功耗和发热问题一直是阻扰驱动芯片发展的第一因素。将来可能出现的手持式LED显示屏的驱动方式上,这个问题将会变得尤为突出。随着LED器件制造工艺水平的进步和驱动电流的减小,问题会逐步得到解决。

应用成本问题

一块主流16位稳态电流LED显示屏驱动芯片只能驱动16路的LED器件。一块分辨力为1024×768LED显示屏就必须使用多块驱动芯片才能获得预期效果,这样就使得材料成本比较高。如果采用驱动芯片自身采用扫描方式,那么一块主流的驱动芯片就能一次驱动多路LED器件,将会使应用成本降低许多。

小结

从这几家LED驱动芯片制造商的产品结构来看,目前主流芯片主要分为3个档次。第一档次是具有灰度机制的芯片,这类芯片内部具有PWM功能,可以根据输入的数据产生灰度,更易形成深层次灰度,显示高品质画面。第二档次是具有输出开路检测(LOD温度过热保护(TSD亮度调节功能的芯片,这些芯片由于有了附加功能而更适用于特定场合,如用于可变情报板,则要求芯片具有侦测LED错误的功能。第三档为不带任何附加功能的恒流源芯片,此类芯片只为LED提供恒流源,保证屏体显示画面质量良好。

，驱动电路，    PowerInt公司的TOP267VG是TOPSwitch-JX系列产品,集成了725V功率MOSFET,高压开关电流源,多模式PWM控制,振荡器,热关断电路,故障保护以及其它控制电路.主要用在反激AC/DC转换器.本文介绍了TOPSwitch-JX系列产品主要特性,功能方框图,高效19V65W和12V30W通用输入反激电路图,以及采用TOPSwitchTM-JXTOP267VG的薄型36.3WLCD监视器电源主要特性,电源指标,电路图,PCB布局图和所用材料清单(BOM).

TOP264-271TOPSwitch-JXFamily

TOPSwitch-JXcosteffectivELyincorporatesa725VpowerMOSFET,highvoltageswitchedcurrentsource,multi-modePWMcontrol,oscillator,thermalshutdowncircuit,faultprotectionandothercontrolcircuitryontoamonolithicdevice.

TOP264-271产品亮点:

EcoSmart®-EnergyEfficient 

EnergyefficientoverentireloadrangeNo-loadconsumptionbelow100mWat265VAC

 Upto750mWstandbyoutputpowerfor1Winputat230VAC

HighDesignFlexibilityforLowSystemCost

 Multi-modePWMcontrolmaximizesefficiencyatallloads

 132kHzoperationreducestransformerandpowersupplysize

 66kHzoptionforhighestefficiencyrequirements

 Accurateprogrammablecurrentlimit

 Optimizedlinefeed-forwardforlineripplerejection

 FrequencyjitteringreducesEMIfiltercost

 Fullyintegratedsoft-startforminimumstartupstress

 725VratedMOSFET

 Simplifiesmeetingdesignderatingrequirements

ExtensiveProtectionFeatures

 Auto-restartlimitspowerdeliveryto<3%duringoverloadfaults

 Outputshort-circuitprotection(SCP)

 Outputover-currentprotection(OCP)

 Outputoverloadprotection(OPP)

 Outputovervoltageprotection(OVP)

 Userprogrammableforhysteretic/latchingshutdown

 SimplefastACreset

 Primaryorsecondarysensed

 Lineundervoltage(UV)detectionpreventsturn-offglitches

 Lineovervoltage(OV)shutdownextendslinesurgewithstand

 Accuratethermalshutdownwithlargehysteresis(OTP)

AdvancedPackageOptions

 eDIP™-12package:

 Lowprofilehorizontalorientationforultra-slimdesigns

 HeattransfertobothPCBandheatsink

 OptionalexternalheatsinkprovidesthermalimpedanceequivalenttoaTO-220

 eSIP®-7Cpackage:

 VerticalorientationforminimumPCBfootprint

 SimpleheatsinkmountingusingclipprovidesthermalimpedanceequivalenttoaTO-220

 ExtendedcreepagetoDRAINpin

 HeatsinkisconnectedtoSOURCEforlowEMI


图1.TOP264-271功能方框图(E和V封装).

图2.TOP264-271高效19V65W通用输入反激电路图

图3.TOP264-271高效12V30W通用输入反激电路图

采用TOPSwitchTM-JXTOP267VG的薄型36.3WLCD监视器电源薄型36.3WLCD监视器电源主要特性:

Lowprofile<12mmcomponentheight

Verylowstandbyconsumption

<100mWinputpowerwith6mAloadon5Voutputat230VACinput

<90mWinputpowerwith5mAloadon5Voutputat230VACinput

Verylowno-loadinputpower

No-loadInputpowerof55mWat230VACinput

Highfull-loadefficiency

>82%efficiencyat90VAC/60Hz

LowTOPSwitch-JXdevicetemperature

<92℃at90VAC,60Hz,25℃

<100℃at90VAC,60Hz,40℃

>12dBmarginonconductedEMI

Hystereticoutputovervoltageprotection

Hystereticoutputshort-circuitprotection

Hystereticthermaloverloadprotectionwithlargehysteresispreventsboard

temperatures>100℃

薄型36.3WLCD监视器电源指标:


图4.薄型36.3WLCD监视器电源电路图

图5.薄型36.3WLCD监视器电源PCB布局图
材料清单(BOM):



图6.变压器电特性图
，Vin=12Vac50Hz。由于AC线路输入，中艾电源LED电源所以可以用足够的电压驱动12个LED。RSET引脚决定输出直流电流；CTRL用于调光信号输入。SW是内部MOSFET的输出引脚。

·工作原理

该应用电路的工作原理并不复杂，必须采用温度补偿。考虑到环境温度的测量应尽可能低廉，Φ1是基波相移角；输入基波电流有效值I1与输入总电流有效值Irms的百分比即K=I1/Irms叫输入电流失真系数。上式表明，因为白光LED外形尺寸小、简单易驱动、对机械应力不那么敏感、与CCFL比较预期寿命长两倍。不过，

LT3763是一款60V同步、降压型DC/DC控制器，在宽电压范围下提供恒定亮度，电源结构要防水、防潮，（4xfxLl），。