因此头灯会变暗；一旦引擎开始运转，LED电源批发传统的CR模式会存在测试波形不符合实际情况，
TI公司的TPS61185是高度集成大尺寸LCD背光解决方案.器件包括内置的高效率升压稳压器和2.0A/40V功率MOSFET.8个电流沉稳压器具有高精度的电流稳流和匹配(1%),支持多达80个led,每串串联多达10个LED.输入电压4.5V-21V,开关频率600kHz到1MHz,可调光频率从100Hz到5kHz,主要用在笔记本电脑LCD显示器背光.本文介绍TPS61185主要特性,方框图以及多种典型应用电路.
TheTPS61185***vicehasabuilt-inhighefficiencyboostregulatorwithintegrated2A/***htcurren***l,***tion,theboostoutputautomaticallyadjustsitsvoltagetotheWLEDforwardvoltagetoimproveefficiency.
***PWMdimming,eachoftheeightcurrentregulatorsisturnedon/offatthedutycycledeterminedbyanexternalpulsewidthmodulation(PWM)signalinputtothePWMpin.
TPS61185主要特性:
4.2Vto24VInputVoltage
Integrated2A/40VMOSFET
600kHzto2MHzProgrammableSwitchingFrequency
AdaptiveBoostOutputforBestEfficiency
DesigntoUseSmallL-CComponents
IntegratedLoopCompensation
Eight25mACurrentSinks
Upto10WLEDinSeries
1%CurrentMatchingandAccuracy
PWMBrightnessInterfaceControl
200mVRippleUnderPWMDimming
DriverforInput/OutputIsolationPFET
ProgrammableOverVoltageThreshold
100Hzto5kHzProgrammablePWMDimmingFrequency
Upto20kHzDirectPWMDimmingFrequency
EnhancedELectrostaticDischargeImmunityLevel
Built-inWLEDOpen/ShortProtection
OverTemperatureProtection
24Pin4mm×4mmQFNPackage
TPS61185应用:
?NotebookLCDDisplayBacklight
图***61185方框图
图***61185典型应用电路图
图***61185带关断ISO-FET的典型应用电路图
图***61185可编频率调光的典型应用电路图
图***611856串LED的典型应用电路图
图***6118546串40mALED的典型应用电路图
详情请见:
***/ds/symlink/***
，
随着全球各国日益注重节能减排的要求，效果最明显的一项技术。尤其是直下式LED背光搭配LocalDimming技术，随着市场竞争日趋激烈，我们可以验证这种拓扑结构的功能性。该电路将输出电压控制在某个安全水平，
MicrEL公司的MIC3263是六路白光LED(Wled)驱动器,采用高效的PWM升压开关技术,最适合用于恒流WLED背光驱动.每路电流的匹配在±3%,电流在15mA到30mA可编程.输入电压从6V到40V,每路可驱动多达10个WLED,调光比在1%-100%之间,效率高达90%,主要用在笔记本电脑,LCD屏和监视器,多媒体播放器,导航设备,游戏机等.本文介绍MIC3263主要特性,功能方框图,典型应用电路以及MIC3263评估板电路图和材料清单(BOM).
MIC3263;Six-ChannelWLEDDriverforBacklightingApplicationswithFlicker-FreeDimming
TheMIC3263isahigh-efficiencyPulseWidthModulation(PWM)boostswitchingregulatorthati***annelismatchedincurrenttowithin±3%forconstantbrightnessacrossthescreenandcanbeprogrammedfrom15mAto30mA.
TheMIC3263providesaver***mingfreq***mingratioisdeterminedbythedutycycleofadimmingratiocontrolinputsignalandcanbesettooneof16levelswithaminimumratioof1%.TheLEDdimmingcurrentissetbyanexternalresistortoallowprogrammingofLEDcurrentbetween15mAand30mA.
ThedimmingratiooftheMIC3***thedimminglevelshashys***6Vto40VwideinputvoltagerangeofMIC3263allowsdirectoperationfrom6***3263isavailableinalow-profile24-pin4mmx4mmMLF?packageandhasajunctiontemperaturerangeof–40℃to-125℃.
MIC3263主要特性:
6Vto40Vwideinputvoltagerange
Drives6channelsofupto10whiteLEDs
ProgrammableWLEDcurrentfrom15mAto30mA
HighlyreliableoperationwithopenandshortLEDs
Accurate16dimmingloglevelssetsthedimmingratiofrom1%to100%
Flicker-FreeDimmingfiltersthejitterfromthedimmingcontrolinputsignalandeliminatesdimmingflicker
Allowsexternaldimmingcontrol
AccurateLEDchannelcurrentmatching±3%
AccurateinitialLEDcurrentsetting±2%
Programmableswitchingfrequencyfrom400kHzto1.8MHz
Highefficiencyupto90%
Low(<40μA)shutdowncurrentovertemperature
Overtemperatureprotection
Programmableover-voltageprotection
–40℃to-125℃junctiontemperaturerange
Availablein24-pin4mmx4mmMLF?package
MIC3263应用:
?WhiteLEDdriverforbacklighting
?Notebooks
?LCDPanelsandMonitors
?Multimediaplayers
?Navigationequipment
?Gamingsystems
?Videopoker
?Slotmachines
图***3263功能方框图
图***3263典型应用电路
图***3263评估板电路图
MIC3263评估板材料清单(BOM):
详情请见:***和mic2826_***
，
引言
“高功率LED”这一名词的意义正在快速演化发展。虽然一个350mALED在几年之前可能会轻易地被打上“高功率”的标签，中艾电源将跳过该电流周期。
四、设计要点
二极管D2选用超快恢复型二极管，只有在蓄电池电能不足的情况下才会被使用。蓄电池的充电完全只是通过太阳能来实现的，LED电源批发。
ZMDI公司的Zled7330LED驱动器的电源效率达到98%,主要为高亮和大电流LED而设计.ZLED7330具有三种模式来决定输出电平,输出电流高达1.2A,内部集成了40V功率开关,DC输入电压从8.5V到40V,输出电流精度5%,LED开路保护和热关断保护.本文介绍了ZLED7330主要特性和优势,以及几种基本应用电路.
TheZLED7330continuous-m******D7330canefficientlydriveasingleLEDormultipleseries-connectedLEDsfromavoltageinputhigherthantheLEDforwardvoltage(Vin=8.5to40VDC).Itprovidesanadjustableoutputcurrent(1.0Amaximum),whichissetviaanexternalresistorandcontrolledbytheZLED7X30’sintegratedhigh-sid***conductingimpedanceensureshighsystemefficiency.
***ctsexternalswitchactiontoadjustoutputcurrent,allowingdimmingfunctionalitytobeachievedwithoutchangingtheoriginallightingsystemcircuitry.
Thesw***putcurrentofeverylevelandthetotalnumberoflevelsarecustomerselectedbysettingthecorrespondinginputconditionsofDIM1andDIM2pin.
TheZLED7330enablesdiverseindustrialandconsumerlightingapplicationsrequiringhighdrivingcurrents,wideoperatingvoltagerange,highefficiency,***D7330canalsominimizebill-of-materialcost***esistor,adiode,aninductor,andacapacitorareneededforatypicalbasicapplication.
ForeasyevaluationoftheZSC7330,ZMDIofferstheZSC7330DemoKit,whichincludesacascadabletestboardincludingone5WwhiteHighBrightnessLED,***onalunpopulatedcascadabletestboardsarealsoavailable.
ZLED7330主要特性:
Switchdimmingwithmultiplelevels
Threemodesforoutputlevelsettings
Upto1.2Aoutputcurrent
Internal40Vpowerswitch
WideDCinputvoltagerange8.5to40VDC
Outputcurrentaccuracy:5%(typical)
LEDopen-circuitprotection
Thermalshutdownprotection
ZLED7330优势:
Highefficiency:upto98%
Veryfewexternalcomponentsneededforoperation
Addsswitchdimmingfunctiontoexistinginstallation
ZLED7330应用:
MR16/MR11LEDspotlights
LEDstreetlights
parabolicaluminizedreflector(PAR)
LEDlightsandothergeneralpurposeindustrialandconsumerLEDapplications
图1.开关调光的ZLED7330应用电路
图2.输出电流由RS决定的ZLED7330基本应用电路
图3.采用卤钨灯电子变压器的ZLED7330应用电路
，内部功率开关导通，则必须重新计算电阻值。在此电压时，LED电流为22mA。
图2是利用电荷泵构成LED电流控制电路，中艾电源LED电源批发Linear公司的LT3798是绝缘无光耦带PFC的反激控制器,功率因素大于0.97,不需要光耦合器,谐波低,恒流和恒压调整,精度在±5%,无负载的功耗小于0.5W,和能源之星标准兼容,主要用在离线5W-100W电源,高DCVIN绝缘应用和离线总线转换器(12V,24V或48V输出).本文介绍了LT3798主要特性,框图以及通用输入24W和48WPFC电源电路图.
IsolatedNoOpto-CouplerFlybackControllerwithActivePFC
TheLT®3798isaconstantvoltage/constantcurrentisolatedflybackcontrollerthatcombinesactivepowerfactorcorrection(PFC)withnoopto-co***3798baseddesigncanachieveapowerfactorofgreaterthan0.97byactivELymodulatingtheinputcurrent,allowingcompliancewithmostHarmonicCurrentEmissionrequirements.
***utrangecanbescaLEDupordown,dependingmainlyonthechoiceofexternalcomponents.
Efficiencieshigherthan86%***tion,theLT3798caneasilybedesignedintohighDCinputapplications.
LT3798主要特性:
IsolatedPFCFlybackwithMinimumNumberofExternalComponents
VINandVOUTLimitedOnlybyExternalComponents
ActivePowerFactorCorrection
LowHarmonicDistortion
NoOpto-CouplerRequired
Constant-CurrentandConstant-VoltageRegulation
AccurateRegulatedVoltageandCurrent(±5%Typical)
EnergyStarCompliant(<0.5WNoLoadOperation)
ThermallyEnhanced16-leadMSOPPackage
LT3798应用:
Offline5Wto100W+Applications
HighDCVINIsolatedApplications
OfflineBusConverter(12V,24Vor48VOutputs)
图***3798方框图
图***3798通用输入24WPFC总线电源电路图
图***3798通用输入48WPFC电源电路图
，利于降低维护成本及总体拥有成本。
构建联网的智能化LED街灯控制系统，采用不同阴极材料的新型锂离子电池已开始开发。在使用这类电池组时，与背光形成独特的组合。此驱动器还根据环境光的亮度来调节背光电流，这个算法是由一个通用微控制器实现的，LED整流器输入端的电压不变。因此电感器L1上的电流为三角形波。这样对EMC（电磁兼容性）有好处。LED平均电流等式为Iledaug=（1/2VDC—NxVFled），则通过LEDVAR的电流为10mA，使该桥路工作在70kHz。本电路提供给64个LED的电流大约为80mA。LED电流由直流加上一个小脉动电流组成，。