AD5203设计的8串白光LED驱动方案

AD5203设计的8串白光LED驱动方案作者：summao来源：本站整理发布时间：2010-6-815:20:40[收藏][评论]AD5203是ADI公司的集成了SMBus和PWM输入的8串白光LED(WLED)驱动器,采用电流模式和升压转换器技术,具有高效率.AD5203集成了0.15Ω,2.9A的开关,工作频率在350kHz和1MHz间选择.输入电压从6V到21V,最大输出电压可调至45V,调光频率在200Hz到10kHz间可调,具有LED开路和短路故障保护.主要用在笔记本电脑,UMPC和监视显示器.本文介绍了AD5203主要特性,方框图以及采用无延迟调光模式的SMBus接口,DPWM调光模式的PWM接口和DC电流调光模式的PWM接口的典型应用电路.8-String,WhiteLEDDriverwithSMBusandPWMInputforLCDBacklightApplicationsTheADD5203isawhiteLEDdriverforbacklightapplicationsbasedonhighefficiency,current-mode,step-upconvertertechnology.Itisdesignedwitha0.15Ω,2.9Ainternalswitchandapin-adjustableoperatingfrequencybetween350kHzand1MHz.TheADD5203containseightregulatedcurrentsourcesforuniformbrightnessintensity.Eachcurrentsourcecanbedrivenupto30mA,andtheLEDdrivingcurrentispinadjustablebyanexternalresistor.TheADD5203drivesuptoeightparallelstringsofmultipleseriesconnectedLEDswitha±1.5%currentmatchingbetweenstrings.TheADD5203providesvariousdimmingmodes.Eachdimmingmodeisselectablewithanexternaldimmingmodeselectionpin.TheLEDdimmingcontrolinterfacecanbeachievedthroughPWMinputand/orSMBus.Thedeviceprovidesadjustableoutputdimmingfrequencyrangefrom200Hzto10kHzbyanexternalresistorandcapacitor.TheADD5203operatesoveraninputvoltagerangeof6Vto21V,butthedevicecanfunctionwithavoltageaslowas5.6V.TheADD5203alsohasmultiplesafetyprotectionfeaturestopreventdamageduringfaultconditions.IfanyLEDisopenorshort,thedeviceautomaticallydisablesthefaultycurrentsource.Theinternalsoftstartpreventsinrushcurrentduringstartup.Thermalshutdownprotectionpreventsthermaldamage.TheADD5203isavailableinalowprofile,thermallyenhanced,4mm×4mm×0.75mm,28-lead,RoHS-compliantleadframechipscalepackage(LFCSP_WQ)andisspecifiedovertheindustrialtemperaturerangeof−25℃to+85℃.AD5203主要特性:WhiteLEDdriverbasedoninductiveboostconverterIntegrated50VMOSFETwith2.9ApeakcurrentlimitInputvoltagerange:6Vto21VMaximumoutputadjustableupto45V350kHzto1MHzadjustableoperatingfrequencyOvervoltageprotection(OVP)uptotypical47.5VBuilt-insoftstartforboostconverterDrivesuptoeightLEDcurrentstringsLEDcurrentadjustableupto30mAforeachchannelHeadroomcontroltomaximizeefficiencyAdjustabledimmingfrequency:200Hzto10kHzLEDopenandshortfaultprotectionSelectabledimmingcontrolinterfacemethodsPWMinputSMBusserialinputSelectabledimmingmodesFixeddelayPWMdimmingcontrolwith8-bitresolutionNodelayPWMdimmingcontrolwith8-bitresolutionDirectPWMdimmingcontrolDCcurrentdimmingcontrolwith8-bitresolutionGeneralThermalshutdownUndervoltagelockout28-lead,4mm×4mm×0.75mmLFCSP_WQAD5203应用:NotebookPCs,UMPCs,andmonitordisplays图1.AD5203电路方框图图2.AD5203典型应用电路:采用无延迟调光模式的SMBus接口图3.AD5203典型应用电路:采用DPWM调光模式的PWM接口图4.AD5203典型应用电路:采用DC电流调光模式的PWM接口