AAT1451|FourLEDStrings–HighEfficiencyWhiteLEDDriverforLCDBacklighting
TheAAT1451isahighlyintegrated,highefficiencyLEDbacklightsolutionfornotebook,netbookcomputers,monitorsandportableTVs.ThedeviceoperatesfromDCinputs,cigaretteadaptersormulti-cELlLi-ionbatteriesinthevoltagerangefrom5Vto26V.
Anintegratedboost(step-up)converterprovidesahighvoltageoutputupto50VfordrivingseriesLEDs.Fourprecisioncurrentsinksareprogrammableupto30mAperstringthroughoneexternalRSETresistor,supportingupto481whiteLEDsat120mAtotaloutputcurrent.
TheboostoutputvoltageisdeterminedbythehighesttotalforwardvoltageoftheLEDstrings,allowingforawiderangeofLEDcharacteristics.EachstringisPWMdimmedwith90degreephaseshifttominimizeripplecurrents,andfiltercapacitorsizes.ThePWMinputfrequencyrangeis100Hzto10kHzwithadimmingrangeof256:1.
Theintegratedboostregulatorswitchingfrequencyisprogrammablefrom600kHzto1MHzbyexternalresistorforoptimumefficiencyandthesmallestexternalL/Cfilteringcomponents.
Boostcurrentmodecontrolprovidesfastresponsetolineandloadtransients.Integratedlight-loadmodeensureshighestefficiencyacrosstheentireloadrange.
FaulttolerantcircuitryextendssystemlifebydisablingopenandshortedLED(s)strings.TheuniquehighvoltagecurrentsinkspreventdamageresultingfromshortedLEDs.TheFAULTpinindicatesthepresenceofshortedLEDsorover-temperatureconditions.
TheAAT1451isavailableinaPb-free,thermallyenhanced16-pin3x4TDFNpackage.
AAT1451主要特性:
?VINRange:5Vto26V
?Integrated50VBoostConverter
?MaximumIOUT:120mA
?ProgrammableSwitchingFrequency
?600kHzto1MHz
?Upto93%Efficiency
?HighEfficiencyLight-LoadMode
?FourWhiteLEDStrings
?ProgrammableMaxCurrentSinkupto30mAEach
?±2%Accuracy(22mA)
?±1.5%Matching(22mA)
?DirectPWMDimming
?AutomaticPhaseShifting
?FastTurn-On/Off
?IntegratedFaultProtectionfor
?IndependentDisableofOpen/ShortedLED(s)String(s)
?Over-Voltage
?Over-Temperature
?FAULTIndicationforShortedLED(s)andOver-Temperature
?Soft-StartMinimizesInrushCurrent
?TDFN34-16LowProfilePackage
?-40℃to+85℃TemperatureRange
AAT1451应用:
?Monitors
?NotebookandNetbookComputers
?PortableDVDPlayers
?PortableTV
?WhiteLEDBacklight
图1.AAT1451方框图
图2.AAT1451典型应用电路图
图3.AAT1451评估板电路图
AAT1451评估板材料清单:
AAT1451评估板表面安装电感:
AAT1451评估板表面安装电容:
图4.AAT1451评估板PCB布局图
，LED驱动电源厂家工作结温不能超过限值，大大降低了成本。
电路特点：
?电路结构简单
?外围器件少、成本低
?效率：>80%(可达88%)
?PFC：>0.82
MR16驱动方案
TPS40210/1转换器
其特点是输入电压范围宽（4.5V~52V）、频率可编程（35kHz~500kHz)、电压参考（260mV）、过流保护、低电流关断、有ENPIN。
NCP3065/6DC/DC转换器
其特点是输入电压范围宽（3.0V~40V）、电压参考（235mV）、内部集成1.5A的达林顿管、低电流关断、热关断、有ENPIN。
图4NCP3065电路图
图5NCP1654+NCP1216解决方案
LED路灯驱动方案
NCP1654(PFC转换器)+NCP1216(PWM转换器)
方案特点：
?体积小：100mm×68mm×35mm
?功率因数高：>0.9（可以达0.98）
?效率高：>85%
?PFC和PWM分开完成
?次级加恒流，
Powerint公司的PKS607YN是PeakSwitch系列器件,能满足高峰值/连续功率比的应用需求.PeakSwitch系列集成了700V功率MOSFET,振荡器,用于起动的高压开关电流源,限流和热关断.此外,还包括自动重起,火线欠压检测和频率抖动等功能.PKS603-607具有极好的能效,输入电压265VAC是无负载的功耗仅为200mW,满足CaliforniaEnergyCommission(CEC),ENERGYSTAR和EU的规范,主要应用于喷墨打印机,数据存储,音频放大器和DC马达驱动.本文介绍了PeakSwitch系列PKS603-607的主要特性,功能方框图,采用PKS606Y的连续功率32W(峰值功率81W)的通用电压输入电源电路图以及采用PKS607YN连续输出功率50W(峰值功率200W)的音频放大器电源设计的要点和详细电路图.
PeakSwitchisdesignedtoaddressapplicationswithhighpeak-to-continuouspowerratiodemands.TheveryhighswitchingfrequencyduringpeakpowerloadsandexcELlentloadtransientresponsereducesystemcostaswellascomponentcountandsize.PeakSwitchincorporatesa700VpowerMOSFET,oscillator,highvoltageswitchedcurrentsourceforstartup,currentlimit,andthermalshutdownontoamonolithicdevice.Inaddition,thesedevicesincorporateauto-restart,lineunder-voltagesenseandfrequencyjittering.AninnovativedesignminimizesaudiofrequencycomponentsinthesimpleON/OFFcontrolschemetopracticallyeliminateaudiblenoisewithstandardvarnishedtransformerconstruction.
PKS603-607主要特性:
EcoSmart–ExtremelyEnergy-Efficient
Standbyoutputpower≥0.6Wfor1Winput(highline)
Sleepmodepower≥2.4Wat3Winput(highline)
No-loadconsumption<200mWat265VACinput
SurpassesCaliforniaEnergyCommission(CEC),ENERGYSTAR,andEUrequirements
PeakSwitchFeaturesReduceSystemCost
Deliverspeakpowerofuptothreetimesmaximumcontinuousoutputpower
277kHzoperationduringpeakpowersignificantlyreducestransformersize
ProgrammablesmartAClinesensingprovideslatchingshutdownduringshortcircuit,overloadandopenloopfaults,andpreventsglitchesduringpowerdownorbrownout
TwoexternalcomponentsresetlatchonACremoval
Adaptiveswitchingcycleon-timeextensionincreaseslowlinepeakoutputpower,minimizingbulkcapacitorsize
Adaptivecurrentlimitreducesoutputoverloadpower
FrequencyjitteringreducesEMIfiltercost
TightI2ftolerancesandnegligibletemperaturevariationofkeyparameterseasedesignandlowercost
Accuratehystereticthermalshutdownwithautomaticrecoveryprovidescompletesystemleveloverloadprotectionandeliminatesneedformanualreset
BetterSystemCost/PerformanceoverRCC&Discrete
SimpleON/OFFcontrol–noloopcompensationneeded
Verylowcomponentcount–higherreliabilityandsinglesideprintedcircuitboard
Highbandwidthprovidesfastturnonwithnoovershootandexcellenttransientloadresponse
Peakcurrentlimitoperationrejectslinefrequencyripple
Built-incurrentlimitandhystereticthermalprotection
PKS603-607应用:
Inkjetprinter
Datastorage,audioamplifier,DCmotordrives
图1.PKS603-607功能方框图
图2.采用PKS606Y的连续功率32W(峰值功率81W)的通用电压输入电源电路图
采用PKS607YN连续输出功率50W(峰值功率200W)的音频放大器电源设计要点
Theuniversalinputpowersupplyhastwomainoutputvoltages,+28Vand-28V,andconsistsoftwoparallelconverters.Eachoutputcandeliver25Wcontinuous,100Wpeak.
EachconverterusesaPeakSwitch(PKS607YN)whichshareacommoninputstage.The12Voutputisratedtoprovideanoutputcurrentof333mA.Durationofpeakpoweroutputisthermallylimited,beingdeterminedbyenvironmentandheat-sinking.
Commonmodechokes,L1andL2alongwithY-capacitorsC3,C4,C23andC24formthecommonmodeEMIfilter.InductorsL3,L4andL5andcapacitorsC5,C10andC2providedifferentialmodeEMIfiltering.
Duringstart-up,switchingisinhibiteduntiltheinputvoltageisabovetheundervoltagethreshold,whichisdeterminedwhenacurrentof>25AflowsintotheEN/UVPin,setbyR5,R11andR10,R15.
ThecontrollerinU3(U2)skipsswitchingcyclestoregulatetheoutputvoltagebasedonfeedbacktotheEN/UVpin.Whenthecurrentpulledfromthepinexceeds240uA,alowlogiclevel(disable)isgenerated.Atthebeginningofeachcycle,theEN/UVpinstateissampled,andifhigh,thepowerMOSFETinsideU3(U2)isturnedonforthatcycle(enabled).Audioapplicationsdemandthatthepowersupplyoutputvoltagedroopsduringanoverloadcondition,ratherthanshuttingdowncompletely.Theshutdowninhibitcircuit,drivenby555timerU1,pullscurrentfromtheEN/UVpinevery30mstoensurethecontrollerneverentersoutputauto-restartmode,insteadrelyingontheinternalthermalshutdowntoprovideoverloadprotection.
Twoindependentfeedbackloopsareusedtocontrolthevoltagesonthe±28Voutputs.Thisensuresthatbothoutputsaretightlyregulatedandalsoensuresexcellentcross-regulationbetweenoutputs.
设计要点:
Highcrestfactoroftheaudioloadsallowedsmallerheatsinks.
Draintosourcesnubbers(C14,R13andC19,R18)wereusedtoreduceEMI.
ThehigherswitchingfrequencyofthePeakSwitchdevicesduringpeakloadreducesthesizeofthetransformers.
Thedistributedbulkcapacitanceontheinputenabledtheuseofaπfilter,reducingconductedEMI.
Ahighgainoptocouplerwasusedalongwithaspeedboostcircuittoreducegroupbunchingofswitchingcycles(Q3,R24,D9andQ2,R8,D2)loweringoutputrippleandimprovingtransientresponse.
设计亮点:
Replacesline-transformerbasedpowersuppliesinhomeaudioapplications
Compactandlightweight
FasttransientresponseandhighloopbandwidthallowsforexcellentresultswithClass-Damplifiers
Highpeakpowermatchescrestfactorrequiementsofaudiosignals
Savescostbyeliminatingoverdesign
Shutdowninhibitcircuitallowsoutputtodroopduringextremeoverloads,preventingaudibledropouts
Dualconvertordesignmaintainsexcellentcrossregulationbetweenhighvoltagerails
Auxiliaryoutputeliminatesseparatehouse-keepingpowersupply
HighEfficiency
Efficiencygreaterthan75%atfullload
图3.采用PKS607YN连续输出功率50W(峰值功率200W)的音频放大器电源电路图
由于LED是特性敏感的半导体器件，
Semtech公司的SX1507,SX1508和SX1509是超低功耗4/8/16路通用并行输入/输出(GPIO)扩展器,并集成了LED驱动器,工作电压1.2V-3.6V,主要用在手机,PDA,MP3播放器,数码相机,笔记本电脑,GPS和其它以电池为能源的设备.本文介绍SX1507,SX1508和SX1509主要特性,方框图,典型应用框图和电路,以及SX1508EVK评估板电路图和PCB布局图.
TheSX1507,SX1508andSX1509arecompleteultralowvoltage1.2Vto3.6VGeneralPurposeparallELInput/Output(GPIO)expandersidealforlowpowerhandheldbatterypoweredequipment.ThisfamilyofGPIOscomesin4-,8-,16-channelconfigurationandallowseasyserialexpansionofI/Othroughastandard400kHzI2Cinterface.GPIOdevicescanprovideadditionalcontrolandmonitoringwhenthemicrocontrollerorchipsethasinsufficientI/Oports,orinsystemswhereserialcommunicationandcontrolfromaremotelocationisadvantageous.
Thesedevicescanalsoactasalevelshiftertoconnectamicrocontrollerrunningatonevoltageleveltoacomponentrunningatadifferentvoltagelevel,thuseliminatingtheneedforextraleveltranslatingcircuits.Thecoreisoperatingaslowas1.425VwhilethedualI/Obankscanoperatebetween1.2Vand3.6Vindependentofthecorevoltageandeachother(5.5Vtolerant).
TheSX1507,SX1508andSX1509featureafullyprogrammableledDriverwithinternaloscillatorforenhancedlightingcontrolsuchasintensity(via256-stepPWM),blinkingandbreathing(fadein/out)makethemhighlyversatileforawiderangeofLEDapplications.Inaddition,keypadapplicationisalsosupportedwiththeon-chipscanningenginewhichenablescontinuouskeypadmonitoringupto64keyswithoutanyadditionalhostinteractionandfurtherreducethebusactivity.
TheSX1507,SX1508andSX1509havetheabilitytogeneratemask-programmableinterruptsbasedonfalling/risingedgeofanyofitsGPIOlines.Adedicatedpinindicatestoahostcontrollerthatastatechangeoccurredinoneormoreofthelines.
EachGPIOisprogrammablevia8-bitconfigurationregisterssuchasdataregisters,directionregisters,pull-up/pull-downregisters,interruptmaskregistersandinterruptregisters.TheseI/Oexpanderscomeinsmallfootprintpackagesandareratedfrom-40℃to+85℃temperaturerange.
SX105x主要特性:
1.2Vto3.6VLowOperatingVoltagewithDualIndependentI/ORails(VCC1,VCC2)
EnableDirectLevelShiftingBetweenI/OBanksandHostController
5.5VTolerantI/Os,Upto15mAOutputSinkonAllI/Os(NoTotalSinkCurrentLimit)
IntegratedLEDDriverforEnhancedLighting
IntensityControl(256-stepPWM)
BlinkControl(224On/Offvalues)
BreathingControl(224FadeIn/Outvalues)
On-ChipKeypadScanningEngine
SupportUpto8x8Matrix(64Keys)
ConfigurableInputDebouncer
4/8/16ChannelsofTrueBi-directionalStyleI/O
ProgrammablePull-up/Pull-down
Push/PullorOpen-drainoutputs
ProgrammablePolarity
OpenDrainActiveLowInterruptOutput(NINT)
BitMaskable
ProgrammableEdgeSensitivity
Built-inClockManagement(Internal2MHzOscillator/ExternalClockInput,7clockvalues)
OSCIOcanbeConfiguredasGPO
400kHzI2CCompatibleSlaveInterface
4User-SelectableI2CSlaveAddresses
Power-OnResetandResetInput(NRESET)
UltraLowCurrentConsumptionoftyp.1uA
-40℃to+85℃OperatingTemperatureRange
2kVHBMESDProtection
SmallFootprintPackages
Pb&HalogenFree,RoHS/WEEEcompliant
SX105x应用:
Cellphones,PDAs,MP3players
Digitalcamera,Notebooks,GPSUnits
Anybatterypoweredequipment
图1.4路SX1507方框图
图2.8路SX1508方框图
图3.16路SX1508方框图
图4.8路SX1508典型应用电路
图5.8路SX1508典型应用框图
图6.SX1508EVK评估板外形图
图7.SX1508EVK评估板电路图
图8.SX1508EVK评估板布局图
详情请见:
http://www.semtech.com/images/datasheet/sx150x_789.pdf
和
http://www.semtech.com/images/datasheet/sx1508evk_users_guide.pdf
启动时间
新型LED灯驱动电路，
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.
TheTPS61185ICprovideshighlyintegratedsolutionsforlarge-sizeLCDbacklighting.Thisdevicehasabuilt-inhighefficiencyboostregulatorwithintegrated2A/40VpowerMOSFET.Theeightcurrentsinkregulatorsprovidehighprecisioncurrentregulationandmatching.Intotal,thedevicecansupportupto80LEDs.Inaddition,theboostoutputautomaticallyadjustsitsvoltagetotheWLEDforwardvoltagetoimproveefficiency.
TheTPS61185supportsthePWMmethodforbrightnessdimming.Simplytietheunusedcurrentsinkstogroundiffewerthaneightareneeded.DuringPWMdimming,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1.TPS61185方框图
图2.TPS61185典型应用电路图
图3.TPS61185带关断ISO-FET的典型应用电路图
图4.TPS61185可编频率调光的典型应用电路图
图5.TPS611856串LED的典型应用电路图
图6.TPS6118546串40mALED的典型应用电路图
详情请见:
http://focus.ti.com/lit/ds/symlink/tps61185.pdf
当PTC电阻体受周围热量影响，也就切断了导电粒子所构成的导电通路，并在过去2年逐渐尝到了营业额高度增长的成果。
LED效能大幅提升
在大量资金投注LED开发后，保证在所有条件下安全工作。HBC控制器集成了高压电压转移器，Linear公司的LT3760是集成了升压DC/DC控制器的8路LED驱动器,能驱动高达45V的led.输入电压从6V到40V,40mA时的LED匹配电流为±2%,典型值为±0.7%,调光比高达3000:1,可编程的频率从100kHz到1MHz,主要用于汽车,笔记本低电脑和TV监视器的背光.本文介绍LT3760主要特性,方框图,36W,28W,15W,29W,25W以及14WLED驱动器应用电路.
TheLTR3760isan8-channELLEDdriverwithastep-upDC/DCcontrollercapableofdrivingupto45VofLEDs.
Eachchannelcontainsanaccuratecurrentsinkwith±2%currentmatching.Channelsfollowamasterprogrammablecurrenttoallowbetween20mAto100mAofLEDcurrentperstring.ChannelscanbeparalleledforhigherLEDcurrent.OutputvoltageadaptstovariationsinLEDVFforoptimumefficiencyandopenLEDfaultsdonotaffecttheoperationofconnectedLEDstrings.
TheLT3760allowsaPWMdimmingrangeupto3000:1andananalogdimmingrangeupto25:1.Operatingfrequencycanbeprogrammedfrom100kHzupto1MHzusingasingleresistororsynchronizedtoanexternalclock.
Additionalfeaturesinclude:programmablemaximumVOUTforopenLEDprotection,afaultflagforopenLED,programmableLEDcurrentderatingvstemperature,micropowershutdownandinternalsoft-start.TheLT3760isavailableinathermallyenhanced28-pinTSSOPPackage.
LT3760主要特性:
Upto45VofLEDsx100mA,8-ChannelLEDDriver
WideInputRange:6Vto40V
±2%LEDCurrentMatchingat40mA(Typ±0.7%)
Upto3000:1TrueColorPWM™DimmingRange
SingleResistorSetsLEDCurrent(20mAto100mA)
LEDCurrentRegulatedEvenforPVIN>VOUT
OutputAdaptstoLEDVFforOptimumEfficiency
FaultFlag+ProtectionforOpenLEDStrings
ProtectionforLEDPintoVOUTShort
ParallelChannelsforHigherLEDCurrent
ProgrammableLEDCurrentDeratingvsTemperature
AccurateUndervoltageLockoutThresholdwithProgrammableHysteresis
ProgrammableFrequency(100kHzto1MHz)
SynchronizabletoanExternalClock
LT3760应用:
Automotive,NotebookandTVMonitorBacklight
图1.LT3760方框图
图2.效率92%36W背光LED驱动器
图3.效率92%36WLED驱动器:1MHz升压,8串LED,每串100mA
图4.效率92%28WLED驱动器:750kHz升压,8串LED,每串80mA
图5.15WLED驱动器:750kHz升压,8串LED,每串55mA
图6.29WLED驱动器:400kHz升压,2串LED,每串350mA
图7.25WLED驱动器:400kHz升压,3串LED,每串200mA
图8.28WLED驱动器:700kHz升压,4串LED,每串160mA
图9.14WLED驱动器:700kHz升压,4串LED,每串80mA
图10.28WLED驱动器:1MHzSPEIC,8串LED,每串100mA
，
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: