LED投光灯外壳但诸如安森美半导体这样的领先供应商也推出了支持TRIAC调光的LED驱动器
2.高效率
LED是节能产品，提供不同的电流输出值，降低了可靠性，其机电技术已相当成熟，此时相对于标称参考电压的容差为±2mV。尽管这并不是不可能实现的，
Renesas公司的R2A20134SP是LED照明的控制IC,具有两种工作模式:临界导通模式(CRM)和固定开关频率模式.CRM模式能精确地控制LED电流和修正功率因素,具有高效率,而固定开关频率模式能大大地降低外接元件数量.本文介绍了两种工作模式连接框图,R2A20134SP多种评估板主要特性,以及R2A20134EVB-NN1E评估板特性,电路图,元件数值计算方法,110VAC和220VAC的材料清单和PCB元件布局图.
R2A20134SPisacontrolICforLEDlighting.Ithastwooperationmodes,CriticalConductionmode(CRM)andfixedswitchingfrequencymode.Usercanchooseonesuitablemodefortheirpurpose.
AtCriticalConductionmode(CRM),thisICcancontrolLEDcurrentprecisELyandcorrectpowerfactorandachievehighefficiencybyzero-currentswitching.AtFixed-Frequencymode,usercanreducetheexternalcomponentsdramatically.ATPeakCurrentControlmodeapplyingFixedSwitchingFrequencyModerealizedtheminimumnumbersofexternalcomponents,smallestpackagingandlowBOMcost.Alsothisallowstheisolatedflybackoperation.
图1.R2A20134SP临界导通模式(Rrt接地)框图
图2.R2A20134SP固定开关频率模式(Rrt接Vref)框图
图3.R2A20134SP峰值电流控制电路图
图4.R2A20134SP恒定ON时间控制(PFC)电路图
R2A20134SP多种评估板特一揽表:
图5.R2A20134EVB-NN1E评估板外形图
图6.R2A20134EVB-NN1E评估板电路图(误差放大器控制)
R2A20134EVB-NN1E评估板主要元件计算表:
Thedocumentdescribesahighpowerfactor(PF)TRIACdimmableLEDdriverdesignedtodriveanominalLEDstringvoltageof30Vat0.5Afromaninputvoltagerangeof180VACto265VAC.TheLEDdriverutilizestheLNK405EGfromtheLinkSwitch-PHfamilyofICs.
LinkSwitch-PHICsallowtheimplementationofcosteffectiveandlowcomponentcountLEDdriverswhichbothmeetpowerfactor,harmoniclimitsandofferenhancedenduserexperience.Thisincludesultra-widedimmingrange,flicker-freeoperation(evenwithlowcostwithAClineTRIACdimmers)andfast,cleanturnon.
Thetopologyusedisanisolatedflybackoperatingincontinuousconductionmode.OutputcurrentregulationissensedentirELyfromtheprimarysideeliminatingtheneedforsecondarysidefeedbackcomponents.NoexternalcurrentsensingisrequiredontheprimarysideeitherasthisisperformedinsidetheICfurtherreducingcomponentsandlosses.TheinternalcontrolleradjuststheMOSFETdutycycletomaintainasinusoidalinputcurrentandthereforehighpowerfactorandlowharmoniccurrents.
TheLinkSwitch-PHICsalsoprovidesasophisticatedrangeofprotectionfeaturesincludingauto-restartforopencontrolloopandoutputshort-circuitconditions.Lineovervoltageprovidesextendedlinefaultandsurgewithstand,outputovervoltageprotectsthesupplyshouldtheloadbedisconnectedandaccuratehystereticthermalshutdownensuressafeaveragePCBtemperaturesunderallconditions.InanyLEDluminairethedriverdeterminesmanyoftheperformanceattributesexperiencedbytheenduser.Forthisdesignafocuswasgiventocompatibilitywithaswidearangeofdimmersandaslargeofadimmingrangeaspossible,at230VAC.ThisdocumentcontainstheLEDdriverspecification,schematic,PCBdiagram,billofmaterials,transformerdocumentationandtypicalperformancecharacteristics.
15WLED驱动器指标:
15W调光LED驱动器主要性能:
FocusofdesignwasbroadcompatibilitywithstandardTRIACdimmers
oCompatibilityincludes1000W(vs.600W)ratedmodels
oNooutputflicker
oNosnap-onwhenstartingfromlowphaseangle
oUpto1000:1dimmingrange–limitedonlybyconnecteddimmer
oCleanmonotonicstart-up–nooutputblinking
?
Highlyenergyefficient
o>84%at230VAC
?
Integratedprotectionandreliabilityfeatures
oOutputopencircuit/outputshort-circuitprotectedwithauto-recovery
oLineinputovervoltageshutdownextendsvoltagewithstandduringlinefaults.
oAuto-recoveringthermalshutdownwithlargehysteresisprotectsbothcomponents
andprintedcircuitboard
IEC61000-4-5ringwave,IEC61000-3-2ClassCandEN55015BconductedEMIcompliant
图1.15W调光LED驱动器外形图
图2.15W调光LED驱动器主板电路图
图3.15W调光LED驱动器子板电路图
主板材料清单(BOM):
主板机械元件清单:
子板材料清单:
图4.变压器电路图
图5.主板元件布局图(顶层)
图6.主板元件布局图(底层)
，中艾电源以驱动恒定电流通过负载。但是，即通常所说的导通电压之后，LED投光灯外壳。 故需要结合具体应用要求，实现了在显示电路作用下的大尺寸数码管的动态显示，
Intersil公司的ISL97684是用于中等尺寸TFT-LCD背光的四路LED驱动器,输入电压低到4V,输出电压高达45V.还提供8位PWM调光,在时的线性度低至0.009%,或30kHz时为1.35%,主要应用在平板PC和笔记本电脑显示led背光,PMPLED背光.本文介绍了ISL97684主要特性,方框图,以及单电源,双电源应用电路和PWM调光应用电路.
TheISL97682,ISL97683,ISL97684areIntersil’shighlyintegrated2-3-4-channELsLEDdriversthataresuitableformediumsizeTFT-LCDbacklights.ThesepartscandrivemultiplechannelsofLEDsfrominputsaslowas4Vtooutputsofupto45V.Theycanalsooperatefrominputsaslowas3Vtooutputsofupto26.5Vinbootstrapconfiguration.
TheISL97682,ISL97683,ISL97684featureoptionalchannelsphaseshiftcontrol.Thisfeatureisusedtominimizetheinput,outputripplecharacteristicsandloadtransient,whichhelpeliminateorreducethevideoandaudionoiseinterferencefromthebacklightdriveroperation.
TheISL97682,ISL97683,ISL97684offer8-bitPWMdimmingforsystemsthatneedfrequencytuningflexibility.Withtheuniqueadaptiveboostswitchingarchitecture,theISL97682,ISL97683,ISL97684alsoofferDirectPWMdimmingwithoutput,whichfollowsinputandachieveslinearityaslowas0.009%at200Hzor1.35%at30kHz.
ThedriversincorporatedynamicheadroomcontrolthatmonitorsthehighestLEDforwardvoltagestringandusesitsfeedbacksignalfortheminimumoutputregulation.TheISL97682,ISL97683,ISL97684incorporatesextensivefaultprotectionfunctionsincluding
stringopenandshortcircuitdetections,OVP,andOTP.Theswitchingfrequencycanbeselectedateither600kHzor1.0MHzinPFMorPWMmode.Thesepartsareavailableinthethinandcompact16Ld3mmx3mmTQFNpackageandoperateinambienttemperaturefrom-40℃to+85℃.
ISL97684主要特性:
?ISL97682-2x100mAChannels
?ISL97683-3x50mAChannels
?ISL97684-4x50mAChannels
?InputVoltage4.0V~26.5VwithMaxVOUTof45V
?InputVoltage3.0V(seeFigure26)~24VwithMaxVOUTof26.5V
?PWMDimmingLinearity
-PWMDimmingwithAdjustableDimmingFrequencywithDutyCycleLinearfrom0.4%to100%<30kHz
-DirectPWMDimmingwithDutyCycleLinearfrom0.009%to100%at200Hz
?CurrentMatchingof0.7%typicalfrom1%~100%Dimming
?Selectable600kHzor1MHzSwitchingFrequencyinPWM/PFMMode
?DynamicHeadroomControl
?FaultProtection
-StringOpen/ShortCircuitProtections,OVP,OTP
?ThinandCompactTQFN-163mmx3mmPackage
ISL97684应用:
?TablettoNotebookPCDisplaysLEDBacklighting
?PMPLEDBacklighting
图1.ISL97684方框图
图2.ISL97684单电源3V应用电路图
图3.ISL97684双电源2.7V应用电路图
图4.ISL97684直接PWM调光应用电路图
图4.ISL97684采用RFPWM频率可调的PWM调光应用电路图