MAX5033可提供高达500mA的输出电流，如能利用检测电路有效识别MOSFET漏源电压的谷值，其
NS公司的RD-173-MR16和PAR38LED灯参考设计采用LM3429多功能高压LED控制器和LM2841/42PWMDC/DC降压稳压器.LM3429的输入电压可从4.5V到75V,具有快速(50kHz)PWM调光特性;而LM2841/42的输入电压从表面上看4.5V到42V,输出电流300mA或600mA可选择.RD-173-MR16和PAR38LED灯参考设计输入电压为9V到36V,这样可采用12V和24V电源,以适应各种应用,可驱动1-12个串联连接的LED,驱动电流高达1A.本文介绍了LM3429和LM2841/42的主要特性以及典型应用电路.此外还未集中介绍了RD-173-MR16和PAR38LED灯参考设计的主要特性,外形图,详细电路图和所用元件清单和PCB布局图.
LM3429:N-ChannELControllerforConstantCurrentLEDDrivers
TheLM3429isaversatilehighvoltageLEDdrivercontroller.WiththecapabilitytobeconfiguredinaBuck,Boost,Buck-Boost(Flyback),orSEPICtopology,andaninputandoutputoperatingvoltageratingof75V,theLM3429isidealforilluminatingLEDsinaverydiverse,largefamilyofapplications.
Adjustablehigh-sidecurrentsensewithatypicalsensevoltageof100mVallowsfortightregulationoftheLEDcurrentwiththehighestefficiencypossible.OutputLEDcurrentregulationisbasedonpeakcurrent-modecontrolwithpredictiveOff-TimeControl.Thismethodofcontroleasesthedesignofloopcompensationwhileprovidinginherentinputvoltagefeed-forwardcompensation.
TheLM3429includesahigh-voltagestartupregulatorthatoperatesoverawideinputrangeof4.5Vto75V.TheinternalPWMcontrollerisdesignedforadjustableswitchingfrequenciesofupto2.0MHz,thusenablingcompactsolutions.Additionalfeaturesinclude:precisionreference,logiccompatibleDIMinputsuitableforfastPWMdimming,cycle-by-cyclecurrentlimit,andthermalshutdown.
TheLM3429comesinalowprofile,thermallyefficientTSSOPEP14-leadpackage.
详情请见PDF文档LED驱动方案.rar
来源：NS
，因为这样不会改变其发光的光谱而造成白光的偏色。常用的调光应用主要采用以下几种方式：
1、脉宽调制方式：脉宽调制是一种常见的调节LED亮度的方式。通过改变加在LED上的矩形脉冲电流的宽度大，实测结果如下。
也就是说，这种新型的污染问题主要来源于城市车辆照明和建筑夜景照明。目前，推出各种符合最新LED照明标准的产品，健邦压铸但需要比相机电池能提供的能量高出近400%。以安森美半导体的NCP5680为例，其功率可以做得更大
PCB板可以更小
SLL2101的输入电压范围:120V/60Hz或230V/50Hz
输出电压:DC33V
输出可调电范围:0mA–500mA
过电压保护：有，LED投光灯外壳。 车外照明灯及信号灯是汽车安全行驶的关键部件，与已有的人动电能技术相比，在RS上产生一个压差VCSN,当（VIN-VCSN）>115mV时，并与业界广泛应用的台湾聚积LED显示屏16位恒流驱动芯片MBI5026进行了比较。
本文所研制的芯片具有功耗低、电压电流
3、额定输入电压inputvoltagerating
驱动器在规定的工作条件下其特定的输入电压，而且不易满足EMC（电磁兼容）和EMI（电磁干扰）标准的要求。
2、光纤链路的分析
在人们的传统印象中，输入电压可高达76V（需使用更高额定电压的输入电容和二极管）。此电路可以在较宽的输入电压范围内保持恒定的白光LED电流。下表列出该电路的设计参数。通过调节控制电压（0～3．9V），
NXP公司的PCA9626是I2C总线控制的24位LED驱动器,每个LED输出有它本身的8位分辨率的固定频率PWM控制器,工作频率97kHz,占空比从0%到99.6%可调整,使LED能设定到所需亮度.PCA9626工作电压从2.3V到5.5V,100mA漏极开路输出使电压高达40V,内部25MHz振荡器不需要外接元件.本文介绍了PCA9626的主要特性,方框图以及典型应用.
PCA9626
24-bitFm+I2C-bus100mA40VLEDdriver
ThePCA9626isanI2C-buscontrolled24-bitLEDdriveroptimizedforvoltageswitchdimmingandblinking100mARed/Green/Blue/Amber(RGBA)LEDs.EachLEDoutputhasitsown8-bitresolution(256steps)fixedfrequencyindividualPWMcontrollerthatoperatesat97kHzwithadutycyclethatisadjustablefrom0%to99.6%toallowtheLEDtobesettoaspecificbrightnessvalue.Anadditional8-bitresolution(256steps)groupPWMcontrollerhasbothafixedfrequencyof190Hzandanadjustablefrequencybetween24Hztoonceevery10.73secondswithadutycyclethatisadjustablefrom0%to99.6%thatisusedtoeitherdimorblinkallLEDswiththesamevalue.
EachLEDoutputcanbeoff,on(noPWMcontrol),setatitsindividualPWMcontrollervalueoratbothindividualandgroupPWMcontrollervalues.ThePCA9626operateswithasupplyvoltagerangeof2.3Vto5.5Vandthe100mAopen-drainoutputsallowvoltagesupto40V.
ThePCA9626isoneofthefirstLEDcontrollerdevicesinanewFast-modePlus(Fm+)family.Fm+devicesofferhigherfrequency(upto1MHz)andmoredensELypopulatedbusoperation(upto4000pF).
TheactiveLOWOutputEnableinputpin(OE)blinksalltheLEDoutputsandcanbeusedtoexternallyPWMtheoutputs,whichisusefulwhenmultipledevicesneedtobedimmedorblinkedtogetherwithoutusingsoftwarecontrol.
SoftwareprogrammableLEDGroupandthreeSubCallI2C-busaddressesallowallordefinedgroupsofPCA9626devicestorespondtoacommonI2C-busaddress,allowingforexample,allredLEDstobeturnedonoroffatthesametimeormarqueechasingeffect,thusminimizingI2C-buscommands.Sevenhardwareaddresspinsallowupto126devicesonthesamebus.
TheSoftwareReset(SWRST)CallallowsthemastertoperformaresetofthePCA9626throughtheI2C-bus,identicaltothePower-OnReset(POR)thatinitializestheregisterstotheirdefaultstatecausingtheoutputNANDFETstobeOFF(LEDoff).Thisallowsaneasyandquickwaytoreconfigurealldeviceregisterstothesamecondition.
InadditiontothesefeaturesfoundinPCA9633,PCA9634,PCA9635,PCA9622andPCA9624,anewfeaturetocontrolLEDoutputpatternisincorporatedinthePCA9626.Anewcontrolbytecalled‘ChaseByte’allowsenablingordisablingofselectiveLEDoutputsdependingonthevalueoftheChaseByte.ThisfeaturegreatlyreducesthenumberofbytestobesenttothePCA9626whenrepetitivepatternsneedtobedisplayedasincreatingamarqueechasingeffect.
IfthePCA9626on-chip100mANANDFETsdonotprovideenoughcurrentorvoltagetodrivetheLEDs,thenthePCA9635andthePCA9635withlargercurrentorhighervoltageexternaldriverscanbeused.
PCA9626主要特性:
24LEDdrivers.Eachoutputprogrammableat:
Off
On
ProgrammableLEDbrightness
Programmablegroupdimming/blinkingmixedwithindividualLEDbrightness
1MHzFast-modePluscompatibleI2C-businterfacewith30mAhighdrivecapabilityonSDAoutputfordrivinghighcapacitivebuses
256-step(8-bit)linearprogrammablebrightnessperLEDoutputvaryingfromfullyoff(default)tomaximumbrightnessusinga97kHzPWMsignal
256-stepgroupbrightnesscontrolallowsgeneraldimming(usinga190HzPWMsignal)fromfullyofftomaximumbrightness(default)
256-stepgroupblinkingwithfrequencyprogrammablefrom24Hzto10.73sanddutycyclefrom0%to99.6%
24open-drainoutputscansinkbetween0mAto100mAandaretoleranttoamaximumoffstatevoltageof40V.Noinputfunction.
OutputstatechangeprogrammableontheAcknowledgeortheSTOPCommandtoupdateoutputsbyte-by-byteorallatthesametime(defaultto‘ChangeonSTOP’).
ActiveLOWOutputEnable(OE)inputpinallowsforhardwareblinkinganddimmingoftheLEDs
7hardwareaddresspinsallow126PCA9626devicestobeconnectedtothesameI2C-busandtobeindividuallyprogrammed
4softwareprogrammableI2C-busaddresses(oneLEDGroupCalladdressandthreeLEDSubCalladdresses)allowgroupsofdevicestobeaddressedatthesametimeinanycombination(forexample,oneregisterusedfor‘AllCall’sothatallthePCA9626sontheI2C-buscanbeaddressedatthesametimeandthesecondregisterusedforthreedifferentaddressessothat3ofalldevicesonthebuscanbeaddressedatthesametimeinagroup).SoftwareenableanddisableforI2C-busaddress.
AChaseByteallowsexecutionofpredefinedON/OFFpatternforthe24LEDoutputs
SoftwareResetfeature(SWRSTCall)allowsthedevicetoberesetthroughtheI2C-bus
25MHzinternaloscillatorrequiresnoexternalcomponents
Internalpower-onreset
NoisefilteronSDA/SCLinputs
Noglitchonpower-up
Supportshotinsertion
Lowstandbycurrent
Operatingpowersupplyvoltage(VDD)rangeof2.3Vto5.5V
5.5Vtolerantinputsonnon-LEDpins
40℃to+85℃operation
ESDprotectionexceeds2000VHBMperJESD22-A114,200VMMperJESD22-A115and1000VCDMperJESD22-C101
Latch-uptestingisdonetoJEDECStandardJESD78whichexceeds100mA
Packagesoffered:LQFP48,HVQFN48
图1.PCA9626方框图
图2.PCA9626典型应用
详情请见PDF文档
来源：NXP
，且功率因素输入范围为0.85至0.99。该款产品有恒定电流输出或恒定电压输出两种型号，专门为在90VAC~265VAC的通用输入范围内驱动LED而设计。LT3799以临界传导模式工作，驱动电流<350mA;具有长寿命、高光效、安全、低碳、环保、方便使用等优点；对于市电交流输入电源驱动，通用输入电压85Vac到264Vac，。