Supertex HV9957带故障保护六路LED驱动方案

SupertexHV9957带故障保护六路LED驱动方案Supertex公司的HV9957是带故障保护六路LED驱动器,包括一个开关模式升压转换器和六个低压降线性稳流器,提供了高效率和精密的电流控制,电流精度达±1.5%,占空比精度达0.5%.每路电流高达30mA,采用相位PWM调光,输出电压额定值56V.保护功能包括欠压,过压,开路/短路,过流和超温等.主要用在多串固态照明和手持led背光照明.本文介绍了HV9957主要特性,简化框图,故障保护框图,典型应用电路以及六路LED驱动器演示板主要特性和指标,电路图,布局图和连接图.Six-ChannELLEDDriverwithIntegratedFaultProtectionTheHV9957LEDdrivercombinesaswitch-modeboostconverterandsixlow-dropoutlinearcurrentregulatorstoprovidetheadvantagesofhighefficiencywithprecisecurrentcontrol.Itmaybeconfiguredformanyapplications,andisespeciallysuitedforonetothreecelllithium-ionpowereddevices.AninternalboostcontrollerwithanintegratedswitcheliminatestheneedforanexternalMOSFET.PhasedPWMdimmingeliminatesaudiblenoise,reducestransientloadontheboostconverter,andminimizessupplycurrentripple.PWMdimmingmaybesynchronizedtoanexternalsignalsuchasthedisplayrefreshrateor,internallygeneratedbyaresistororcrystaloscillator.Faultprotectionisprovidedagainstopen/shortedLEDs,overvoltage,undervoltage,overcurrent,andovertemperatureconditions.Whenastringfails,eithershortedoropen,theaffectedchannelisremovedfromfeedbackandtherestcontinueoperatingnormally.HV9957主要特性:DrivessixstringsofLEDs,upto30mAeachPhasedPWMdimmingPin-programmabledimmingfrequencyorsynchronizabletoanexternalsignalPWMdimmingtoverylowdutycycles±1.5%typicalcurrentand0.5%dutycyclematchingOptionalcrystaloscillatorforprecisiondimmingfrequencyOutputsratedto56VRobustprotectionagainstundervoltage,overvoltage,open/shortedstrings,overcurrent,andovertemperature.Goodstringsremainlit.Programmableboostconverterfrequency10μAmaximuminputcurrentinshutdownstateResistor-programmablefull-scaleLEDcurrent24-Lead4×4QFNpackageHV9957应用:Multi-stringsolid-statelightingapplicationsPortableLEDbacklightingapplications图1.HV9957简化框图图2.HV9957故障保护框图图3.HV9957典型应用电路六路LED驱动器演示板TheHV9957LEDdrivercombinesaswitch-modeboostconverterandsixlow-dropoutlinearcurrentregulatorstoprovidetheadvantagesofhighefficiencywithprecisecurrentcontrol.六路LED驱动器演示板主要特性:►►Phaseddimming►►Temperature-triggeredfaultyLEDprotection►►Smart‘outlier’faultystringdiscrimination►►Overcurrentprotection►►Precisedimmingfrequency►►Accuratechannelmatching六路LED驱动器演示板指标:图4.六路LED驱动器演示板电路图六路LED驱动器演示板材料清单:图5.六路LED驱动器演示板布局图和连接图