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传动装置led信号源的数据交换旁路光电开关电源线

102019-08-21 15:36

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NS公司的LM3445是TRIAC调光兼容的自适应离线AC/DC降压恒流控制器,具有LED调光用的TRIAC调光译码电路,输入电压从80VAC到270VAC,控制LED电流大于1A,可调整开关频率.它的无源PFC电路使得电路有更好的效率.LM3445主要用在后配合的TRIAC调光,固态照明,工业和商业照明以及住宅区照明.本文介绍了LM3445的主要特性,简化方框图,典型应用电路,主从配置框图以及带Valley-Fill电路的主/从配置框图,LM3445设计案例电路图和材料清单,LM3445评估板电路图和材料清单.此外还介绍了LM3445离线TRIAC调光LED驱动器参考设计(120V和230V)与材料清单.TheLM3445isanadaptiveconstantoff-timeAC/DCbuck(step-down)constantcurrentcontrollerdesignedtobecompatiblewithtriacdimmers.TheLM3445providesaconstantcurrentforilluminatinghighpowerLEDsandincludesatriacdimdecoder.ThedimdecoderallowswiderangeLEDdimmingusingstandardtriacdimmers.Thehighfrequencycapablearchitectureallowstheuseofsmallexternalpassivecomponents.TheLM3445includesableedercircuittoensurepropertriacoperationbyallowingcurrentflowwhilethelinevoltageislowtoenableproperfiringofthetriac.ApassivePFCcircuitensuresgoodpowerfactorbydrawingcurrentdirectlyfromthelineformostofthecycle,andprovidesaconstantpositivevoltagetothebuckregulator.Additionalfeaturesincludethermalshutdown,currentlimitandVCCunder-voltagelockout.LM3445主要特性:■TriacdimdecodercircuitforLEDdimming■Applicationvoltagerange80VAC?C270VAC■CapableofcontrollingLEDcurrentsgreaterthan1A■Adjustableswitchingfrequency■Lowquiescentcurrent■Adaptiveprogrammableoff-timeallowsforconstantripplecurrent■Thermalshutdown■No120Hzflicker■Lowprofile10pinMSOPPackage■PatentpendingdrivearchitectureLM3445应用:■RetroFitTriacDimming■SolidStateLighting■IndustrialandCommercialLighting■ResidentialLighting图LM3445LED驱动器典型应用电路图LM3445简化方框图图LM3445的主从配置框图图带分开的Valley-Fill电路的主/从配置框图图带一个Valley-Fill电路的主/从配置框图图LM3445设计案例电路图Input=90VACto135VAC,VLED=7xHBLEDStringApplication@400mA材料清单(BOM):图LM3445评估板电路图LM3445评估板材料清单(BOM):LM3445离线TRIAC调光LED驱动器参考设计LM3445Off-LineTRIACDimmerLEDDriverReferenceDesignThisreferencedesignconverts90VACto135VACinput,anddrivesseven,oreightseriesconnectedLEDsfrom300to600mAaveragecurrent..TheLM3445switchingfrequencyissetatanominal225kHz.Thisisafourlayerboardusingthebottomandtoplayerforcomponentplacement.ThereferencedesigncanbemodifiedtoadjusttheLEDforwardcurrent,thenumberofseriesconnectedLEDsandswitchingfrequency.Asecondaryschematicfora230VACimplementationisalsoincluded.图LM3445EVB120V电路图图LM3445230V参考电路图图1LM3445TRIACEVAL板外形图(120V)详情请见PDF文档Desktop.rar。·输入电压范围:85V~265VAC。双相位PWM模块是按置位/复位原理工作的“模拟”式PWM模块。·输入频率范围:47~100Hz。降压-升压转换器可按图1的方式实现。·功率因数≥95。注意到设置值从50mV步长变到100mV步长处有清楚的反射点。NS的LM3421/LM3423是恒流LED驱动器的N沟控制器,可配置成降压,升压,降-升压(反激)或SEPIC,输入电压可高达75V,非常适合各种情况下的LED照明应用.采用LM3423的环境光自适应LED驱动器采用5V-12V的电池输入,在15-20V时LED保持100mA的恒流,效率高达85%,PWM标LED调光高达25kHz,可使LED的亮度正比与环境光,从而延长了电池使用寿命.本文介绍了LM3421/LM3423的主要特性,方框图以及相应的应用电路.同时还介绍了采用LM3423的环境光自适应LED驱动器的主要特性,详细的电路图和材料清单(BOM).LM342LM3423:N-ChannELControllersforConstantCurrentLEDDriversTheLM3421/LM3423devicesareversatilehighvoltageLEDdrivercontrollers.WiththecapabilitytobeconfiguredinaBuck,Boost,Buck-Boost(Flyback),orSEPICtopology,andaninputoperatingvoltageratingof75V,thesecontrollersareidealforilluminatingLEDsinaverydiverse,largefamilyofapplications.Adjustablehigh-sidecurrentsensewithatypicalsensevoltageof100mVallowsfortightregulationoftheLEDcurrentwiththehighestefficiencypossible.OutputLEDcurrentregulationisbasedonpeakcurrent-modecontrolwithpredictiveOff-TimeControl.Thismethodofcontroleasesthedesignofloopcompensationwhileprovidinginherentinputvoltagefeed-forwardcompensation.TheLM3421/LM3423includeahigh-voltagestartupregulatorthatoperatesoverawideinputrangeof5Vto75V.TheinternalPWMcontrollerisdesignedforadjustableswitchingfrequenciesofupto0MHz,thusenablingcompactsolutions.Additionalfeaturesinclude:“zero”currentshutdown,precisionreference,logiccompatibleDIMinputsuitableforfastPWMdimming,cycle-by-cyclecurrentlimit,andthermalshutdown.TheLM3423alsoincludesanLEDoutputstatusflag,afaultflag,aprogrammablefaulttimer,andalogicinputtoselectthepolarityofthedimmingoutputdriver.LM3421/LM3423主要特性:■VINrangefrom5Vto75V■2%Internalreferencevoltage(235V)■urrentsensevoltageadjustablefrom20mV■High-sidecurrentsensing■2ΩMOSFETgatedriver■DimmingMOSFETgatedriver■Inputunder-voltageprotection■Over-voltageprotection■Lowshutdowncurrent,IQ<1μA■Fast(50kHz)PWMdimming■Cycle-by-cyclecurrentlimit■Programmableswitchingfrequency■LEDoutputstatusflag(LM3423only)■Faulttimerpin(LM3423only)■TSSOPEP16-leadpackage(LM342■TSSOPEP20-leadpackage(LM342LM3421/LM3423应用:■LEDDrivers■Constant-CurrentBuck-BoostRegulator■Constant-CurrentBoostRegulator■Constant-CurrentFlybackRegulator■Constant-CurrentSEPICRegulator■Thermo-ElectricCooler(Peltier)Driver图LM3421典型应用电路图LM3421/LM3423方框图图带高速调光的LM3421降-升压电路图图带高速调光的LM3421SEPIC电路图图带高速PWM调光和对VLED恒定的波纹电流的LM3421降压电路图图带高速PWM调光和对VIN恒定的波纹电流的LM3421降压电路图图LM3423全特性应用电路图:带高速PWM调光,故障保护和输入断开开关图带高速PWM调光的LM3423降压电路图采用LM3423的环境光自适应LED驱动器AmbientLightAdaptiveLEDDriverTheambientlightadaptiveLEDdriverautomaticallyadjustsdisplaybrightnessforchangingambientlightconditions,providingamoreviewabledisplaywithbettercontrast.ThedesigndrivesfiveseriesconnectedLEDsfromaninputvoltageof5Vto12V.TheLEDcurrentisnominally100mAandtheoutputvoltageis15to20V.TheheartofthedesignisNational’sPowerWiseLM3423LEDdriverwhichhasallthefeaturesneededtoimplementaboostconverterwithoutputcurrentregulationandPWMdimmingofthecurrent.TheLM3423achievesoutputcurrentregulationbysensingandappropriatelyadjustingthevoltageacrossaresistorconnectedinserieswiththeLEDstring.Dimmingorbrighteningthebacklightofadisplayinresponsetoambientlightconditioncangreatlyincreasethelifeofbatteriesinportabledevices,andimprovesthevisibilityofthedisplayunderdifferentviewingconditions.InthisdesignaphotodiodecircuitisusedtomeasureambientlightandprovideasignalfordimmingtheLEDs.PWMdimmingisthepreferredmethodofdimmingbecauseitallowsthelight’scolortemperaturetoremainconstantirrespectiveofitsintensity.PWMdimmingisdonebykeepingtheamplitudeoftheLEDcurrentconstant,butperiodicallyturningtheLEDdriveronandoff,thusvaryingtheLEDs’averagecurrentandlightintensity.Theswitchingisatdoneatalowfrequency,butonewhichishighenoughforthehumaneyetosenseonlychangesinthelight’saverageintensity.Lineardimming,wheretheamplitudeofthecurrentintheLEDsismodulated,isnotsuitablebecausetheLEDs’lightcolortemperatureissensitivetothecurrent’samplitude.ThedimmingrangeoftheaverageLEDcurrentisfrom20tonearly100%percentofitsnominalvalueasambientlightconditionsincreasefromdarktobright.Toreducepowerconsumptionandprolongbatterylifetheoutputcurrentisclampedtonomorethan50%ofthenominalvaluewhentheinput(battery)voltagefallsbelowapredeterminedlevel.环境光自适应LED驱动器主要特性:■5-12Vbatteryinputvoltagerange■100mAConstantcurrentLEDat15-20V■Highswitchingfrequency■Highefficiency(85%)■PWMLEDdimmingupto25kHz■LEDbrightnesslimitedtolessthan50%ofmaximumatlowinputvoltagetoprolongbatterylife■LEDbrightnessproportionaltoambientlight图环境光自适应LED驱动器外形图图1环境光自适应LED驱动器电路图材料清单(BOM):来源:NS。图6是一种典型应用情况,CP2130/1/3采用QFN3*3mm216引脚的封装,同时外围元件相当简单,只需要4个电容。考虑SMPS的电感在连续模式中工作的情况(通过电感的电流波形参见图。图2简化的降压调节器电路图更仔细的观察这个设计中的储能元件可以发现一些有趣的观点。本文描述的电路满足了驱动高功率并联LED阵列的目标。在这种情况下,负载电流改变,将增加LED阵列上的压降。用MAX15005将8V至16V汽车电池升压至21V,以驱动一串6至8个LED。利用RC滤波器对PWM信号进行滤波,从而获得一个模拟电压并将它输送给比较器的负输入端。利用这一电路及软件调整LED亮度有两种方法。PWM时钟信号确定基本的PWM频率。彩色LED是向用户报告来电和电池充电情况的良好指示器。·新颖的调光功能。·保护功能齐全。

本文重点就中小尺寸的LCD显示屏的背光驱动解决方案作一个分析介绍。在开关节点存在高dV/dT的情况下,下部MOSFETM2可以通过它自己的漏极-栅极电容导通。CS5165A提供了一定的不重叠时间,但是增加这个电路的收获更多。在CP2126的设计中注意了两个问题:避免了EMI的干扰问题CP2126避免了一般的串联型LED驱动电路中电感和大电流开关所产生的EMI干扰问题,对于诸如MPPMP之类的应用场合,这个问题可能影响不大,但是在手机应用中,EMI干扰会造成手机的接收灵敏度变差。PIC16HV785混合信号单片机集成了一个8位单片机内核和多个片上模拟外设,包括:一个高速双相位PWM电路,对于开关电源的电流模式控制非常适合。这个电压足够使上部MOSFETM1导通时关断M2。图3:两倍电荷泵驱动电路。以超薄电子灯箱为例,导光板两侧用BL8532作为LED光源的驱动,一颗BL8532最多可驱动32颗小功率白光LED,采用二串十六并的模式,如图1所示。

·输出效率:≥92%。根据串联结的类型和数量,LED两端的正向压降可能不同。TheIRS2540/1isatime-delayedhystereticBuckcontroller.DuringnormaloperatingconditionstheoutputcurrentisregulatedviatheIFBpinvoltagetoanominalvalueof500mV.Thisfeedbacksignaliscomparedtoaninternalhighprecisionbandgapvoltagereference.Anon-boarddV/dtfilterhasalsobeenusedtopreventerroneoustransitioning.ThisisnecessarysincetheIFBpinissensitivetonoise.OncetheVCCsupplytotheIR2540reachesVCCUV+theLOoutputisheldhighandtheHOoutputlowforapredeterminedperiodoftime.ThisinitiateschargingofthebootstrapcapacitorestablishingtheVBSfloatingsupplyforthehighsideoutput.ThechipthenbeginstogglingHOandLOoutputsasneededtoregulatetheloadcurrent.monitoredandfedbackthroughRCSshowninfig1Thedeadtimesofapproximately140nsbetweentheLOandHOgatedrivesignalsprevent“shootthrough”andreduceswitchinglosses,particularlyathigherfrequencies.图IRPLLED1外形图图采用IRS2540/1的恒流LED驱动电路图IRS2540/1ConstantCurrentLEDDriverTypicalSchematic图采用IRS2540/1的时延滞后控制评估板电路图AlternateIRS2540/1Time-DelayedHystereticControlledEvaluationBoardSchematic材料清单(BillofMaterials):详情请见PDF文档Desktop.rar来源:IR。