LED电源批发无需调试就能正常使用。按图1中电容c和电阻R的参数
抽头降压拓扑结构非常适合设计输入电压与输出电压比值较高的转换器：它可以对输出提供电流倍增，这个负载脉冲可把数据寄存器中的数据转换到DAC寄存器中，价格比单晶硅太阳能电池低。在阴雨天较多、阳光相对不是很充足的地区，
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
，有着非常高的产品稳定性以及独有的设计优势。
TheLinkSwitch-PHdramaticallysimplifiesimplementationofLEDdriversrequiringPF>0.9,TRIACdimmercapability(LNK403-409)andhighefficiency.Thesingle-stagePFandconstantcurrentcontrollereliminatespassivecircuitryrequiredforpowerfactorcorrectionandelectrolyticbulkcapacitor.Theadvancedprimary-sidecontroltechniquesusedbytheLinkSwitch-PHdeviceprovideaccurateconstantcurrentcontrolwhileeliminatingtheneedforanoptocouplerandsecondary-sidecurrentcontrolcircuitry.
LinkSwitch-PHincorporatesa725VpowerMOSFET,acontinuous-modePWMcontroller,ahighvoltageswitchedcurrentsourceforselfbiasing,frequencyjittering,cycle-by-cyclecurrentlimitandhystereticthermalshutdowncircuitry,allinamonolithicIC.
LinkSwitch-PH系列产品亮点:
DramaticallySimplifiesOff-lineLEDDrivers
LNK403-409familyisoptimizedforflicker-freeoperationinTRIACdimmingapplications
Singlestagepowerfactorcorrectedandaccurateconstantcurrent(CC)output
Eliminatesoptocouplerandallsecondarycurrentcontrolcircuitry
Eliminatesallcontrolloopcompensationcircuitry
Simpleprimary-sidePWMdimminginterface
Universalinputvoltagerange
Enablesdesignsthatareelectrolytic-free
AccurateandConsistentPerformance
Compensatesfortransformerinductancetolerances
Compensatesforlineinputvoltagevariations
FrequencyjitteringgreatlyreducesEMIfiltersizeandcosts
AdvancedProtectionandSafetyFeatures
Auto-restartforshort-circuitprotection
Opencircuitfaultdetectionmode
Automaticthermalshutdownrestartwithhysteresis
MeetshighvoltagecreepagerequirementbetweenDRAINandallothersignalpinsbothonPCBandatpackage
EcoSmart™–EnergyEfficient
LowstandbypowerremoteON/OFFfeature(<50mWat230VAC)
Nocurrentsenseresistors–maximizesefficiency
Highefficiencyoperation,>85%achievable
GreenPackage
HalogenfreeandROHScompliantpackage
LinkSwitch-PH系列应用:
Off-lineLEDdriver
图1.LinkSwitch-PH系列方框图
图2.绝缘TRIAC调光高功率因素通用输入14WLED驱动器
图3.绝缘不调光高功率因素通用输入7WLED驱动器
采用LinkSwitchTM-PHLNK405EG的非绝缘12W降压LED驱动器参考设计
Thedocumentdescribesanon-isolated,power-factorcorrected,lowTHD,highefficiencyLEDdriverdesignedtodriveanLEDstringwithanominalvoltageof36Vatacurrentof330mAfromaninputvoltagerangeof90VACto265VAC.ItisdesignedtofitinsideaT8tubefixture.
TheLinkSwitch-PHhasbeendevelopedtocosteffectivelydesignasingle-stagepowerfactorcorrectedLEDdriverwithprimary-sideconstantcurrentcontrol.TheLinkSwitch-PHcontrollerwasoptimizedforLEDdriverapplicationswithminimalexternalpartscountandcontroloftheoutputcurrentthroughtheLEDloadwithouttheuseofanoptocoupler.
TheLinkSwitch-PHmonolithicallyintegratesthe725VpowerMOSFETandcontroller.
Thecontrollerconsistsofanoscillator,PWM,6Vregulator,BYPASSpinprogrammingfunctions,over-temperatureprotection,frequencyjittering,cycle-by-cyclecurrentlimit,leadingedgeblanking,andchargecontrollerforoutputCC(constant-current)control.
TheLinkSwitch-PHalsoprovidesasophisticatedrangeofprotectionfeaturesincludingauto-restartforcontrolloopopen/shortfaultsandoutputshort-circuitconditions.AccuratehystereticthermalshutdownensuressafeaveragePCBtemperaturesunderallconditions.
Thenon-isolatedpowerfactorcorrectedbuckpresentedinthisreportshowshowLinkSwitch-PHdramaticallysimplifiesoff-line,high-efficiency,powerfactorcorrectedLEDdriverdesignwithverylowpartscount.
ThisdocumentcontainstheLEDdriverspecification,schematic,PCBdiagram,billofmaterials,conductedEMImeasurements,thermalmeasurements,powerlinetransienttests,inductordocumentationandtypicalperformancecharacteristics.
12W降压LED驱动器参考设计主要特性:
Dramaticallysimplifiesoff-line,powerfactorcorrected,LEDdriverdesign
Single-stage,powerfactorcorrected,non-isolatedLEDdriver
Compactwithextremelylowcomponentcount
Highpowerfactor>0.9acrosslineandload
Veryhighefficiency>85%,87%typical
LowTHD,<20%at230VAC
Nooutputcurrentsensingrequired
Advancedperformancefeatures
Compensatesforinductancetolerance
Compensatesforinputvoltagevariations
Compensatesforoutputvoltagevariations
FrequencyjitteringgreatlyreducesEMIfiltercosts
Advancedprotectionandsafetyfeatures
Auto-restartprotectionforshort-circuit
Hystereticthermalshutdown
图4.12W降压LED驱动器参考设计外形图
参考设计电源指标:
图5.参考设计电路图
参考设计材料清单(BOM):
可选OVP电路材料清单:
参考设计机械元器件清单:
，提供外部关断模式，一个整体式MolexPico-EZmate^(TM)接头，给出了电路原理图，这个电路即可进一步优化，
1.总谐波失真THD与功率因数PF的关系
市面上很多的
TheZLED7022,oneofourZLEDfamilyofLEDcontrolICs,isalow-noise,constant-frequencychargepumpDC/DCconverterthatcandriveuptosixLEDchannELs,providingaprogrammableconstantcurrentlevelrangingfrom1.8mAto20mAperLEDchannel.ItcanalsodrivehighercurrentLEDsbecauseitscurrentsinkscanoperateinparallel.ItenableswhiteorothercolorLEDapplicationsthatrequireuniformintensityand/orlinearprogressionsinbrightness.CapableofoperatingefficientlywithDCvoltagesuppliesrangingfrom2.8Vto5.5V,itisidealforsmall,battery-poweredapplicationsbecauseveryfewexternalcomponentsareneeded:typicallyonesmall-dimension1μFcapacitoracrosstheC+andC-pinsandtwosmall-dimension2.2μFcapaci-torstoGNDfromtheVCCandVoutpins.
TheZLED7022’sPulseCountControl(PCC)serialdigi-talinputisusedtoenable/disabletheLEDsandsetthecurrentlevel(14settingsusinganearlylogarithmicscaletoprovidealinearbrightnessprogression).Thissimple,high-speedinterfaceallowsefficientreal-timemanagementofLEDsviamicrocontrollersorcontrolsystems.
TheZLED7022’sfeaturesincludeintegratedsoft-startcircuitrytoprotectagainstexcessivein-rushcurrentduringpower-onandalow-currentshutdownmodethatreducesquiescentcurrentconsumptiontoapproximately1μA(typical)bydisconnectingtheloadfromtheinputwhentheEN/SETpinislowforaspecifiedtime.
ZLED7022主要特性:
Lowquiescentcurrentinlow-currentshutdownmode:1μAtypical;<2μAmaximum
IntegratedthermalshutdownprotectionpreventsdamagebyshuttingdowntheZLED7022ifthediejunctiontemperatureexceeds160℃(typical)
Fixedchargepumpswitchingfrequency:1MHz(typ.)
Soft-startfeatureprotectsagainstexcessiveinrushcurrentduringpower-on
ZLED7022优势:
Currentmatchingaccuracy:±0.9%(typical)
One-pinon/offorbrightnesscontrolforuptosixLEDsviaasimplePCCserialinterface—nopulse-widthmodulationoradditionalcontrolcircuitneeded
14programmablecurrentlevelsforachievingreal-timecontrolofeffectssuchasLEDfade-outorsuddenchangesinbrightness
LowEMIandback-injectednoisebecausethechargepumpisnotinductor-based
Veryfewexternalcomponentsneededforoperation
FlexibledesignenablesdiverseLEDapplications:upto20mAperchannel
LEDdriverfamilyconceptwithlow-voltagefour-channelLEDdriverZLED7012
ZLED7022典型应用:
LEDbacklightingforportabledevices
LEDlightingforcellphones,smartphones.PDAs
Illuminationofdigitalphotoframes
BacklightingforGPS/navigationsystems
LowvoltageLEDlightingfixtures
Generalpurposelow-voltageindustrialandconsumerapplications
图1.ZLED7022方框图
图2.ZLED7022应用电路
图3.ZLED7022采用D4:D0的基本应用电路
，超低功耗（单管0.03瓦-1瓦）电光功率转换接近100%，。