3. MP2488DN-LF-Z 应用于60V Vin内路灯系统， PowerInt公司的TOP267VG是TOPSwitch-JX系列产品,集成了725V功率MOSFET,高压开关电流源,多模式PWM控制,振荡器,热关断电路,故障保护以及其它控制电路.主要用在反激AC/DC转换器.本文介绍了TOPSwitch-JX系列产品主要特性,功能方框图,高效19V65W和12V30W通用输入反激电路图,以及采用TOPSwitchTM-JXTOP267VG的薄型36.3WLCD监视器电源主要特性,电源指标,电路图,PCB布局图和所用材料清单(BOM).
TOP264-271TOPSwitch-JXFamily
TOPSwitch-JXcosteffectivELyincorporatesa725VpowerMOSFET,highvoltageswitchedcurrentsource,multi-modePWMcontrol,oscillator,thermalshutdowncircuit,faultprotectionandothercontrolcircuitryontoamonolithicdevice.
TOP264-271产品亮点:
EcoSmart®-EnergyEfficient
EnergyefficientoverentireloadrangeNo-loadconsumptionbelow100mWat265VAC
Upto750mWstandbyoutputpowerfor1Winputat230VAC
HighDesignFlexibilityforLowSystemCost
Multi-modePWMcontrolmaximizesefficiencyatallloads
132kHzoperationreducestransformerandpowersupplysize
66kHzoptionforhighestefficiencyrequirements
Accurateprogrammablecurrentlimit
Optimizedlinefeed-forwardforlineripplerejection
FrequencyjitteringreducesEMIfiltercost
Fullyintegratedsoft-startforminimumstartupstress
725VratedMOSFET
Simplifiesmeetingdesignderatingrequirements
ExtensiveProtectionFeatures
Auto-restartlimitspowerdeliveryto<3%duringoverloadfaults
Outputshort-circuitprotection(SCP)
Outputover-currentprotection(OCP)
Outputoverloadprotection(OPP)
Outputovervoltageprotection(OVP)
Userprogrammableforhysteretic/latchingshutdown
SimplefastACreset
Primaryorsecondarysensed
Lineundervoltage(UV)detectionpreventsturn-offglitches
Lineovervoltage(OV)shutdownextendslinesurgewithstand
Accuratethermalshutdownwithlargehysteresis(OTP)
AdvancedPackageOptions
eDIP™-12package:
Lowprofilehorizontalorientationforultra-slimdesigns
HeattransfertobothPCBandheatsink
OptionalexternalheatsinkprovidesthermalimpedanceequivalenttoaTO-220
eSIP®-7Cpackage:
VerticalorientationforminimumPCBfootprint
SimpleheatsinkmountingusingclipprovidesthermalimpedanceequivalenttoaTO-220
ExtendedcreepagetoDRAINpin
HeatsinkisconnectedtoSOURCEforlowEMI
图1.TOP264-271功能方框图(E和V封装).
图2.TOP264-271高效19V65W通用输入反激电路图
图3.TOP264-271高效12V30W通用输入反激电路图
采用TOPSwitchTM-JXTOP267VG的薄型36.3WLCD监视器电源薄型36.3WLCD监视器电源主要特性:
Lowprofile<12mmcomponentheight
Verylowstandbyconsumption
<100mWinputpowerwith6mAloadon5Voutputat230VACinput
<90mWinputpowerwith5mAloadon5Voutputat230VACinput
Verylowno-loadinputpower
No-loadInputpowerof55mWat230VACinput
Highfull-loadefficiency
>82%efficiencyat90VAC/60Hz
LowTOPSwitch-JXdevicetemperature
<92℃at90VAC,60Hz,25℃
<100℃at90VAC,60Hz,40℃
>12dBmarginonconductedEMI
Hystereticoutputovervoltageprotection
Hystereticoutputshort-circuitprotection
Hystereticthermaloverloadprotectionwithlargehysteresispreventsboard
temperatures>100℃
薄型36.3WLCD监视器电源指标:
图4.薄型36.3WLCD监视器电源电路图
图5.薄型36.3WLCD监视器电源PCB布局图
材料清单(BOM):
图6.变压器电特性图
，隧道， 在全球能源短缺、环保要求不断提高的背景下，倾向使用低上许多的链波电流。另外，中艾电源以便限制了输出电流超过期望的LED驱动电流。其抵消了总LED正向电压随温度和器件容差的变化，并得出合理的稳定供应电流。
dsPIC33主要特性:
OperatingRange:
?Upto40MIPSoperation(at3.0-3.6V):
-Industrialtemperaturerange(-40℃to+85℃)
-Extendedtemperaturerange(-40℃to+125℃)
High-PerformanceDSCCPU:
?ModifiedHarvardarchitecture
?Ccompileroptimizedinstructionset
?16-bitwidedatapath
?24-bitwideinstructions
?Linearprogrammemoryaddressingupto4Minstructionwords
?Lineardatamemoryaddressingupto64Kbytes
?83baseinstructions:mostly1word/1cycle
?Two40-bitaccumulatorswithroundingandsaturationoptions
?Flexibleandpowerfuladdressingmodes:
-Indirect
-Modulo
-Bit-Reversed
?Softwarestack
?16x16fractional/integermultiplyoperations
?32/16and16/16divideoperations
?Single-cyclemultiplyandaccumulate:
-AccumulatorwritebackforDSPoperations
-Dualdatafetch
?Upto±16-bitshiftsforupto40-bitdata
DirectMemoryAccess(DMA):
?4-channELhardwareDMA
?1KbytedualportedDMAbufferarea(DMARAM)tostoredatatransferredviaDMA:
-AllowsdatatransferbetweenRAMandaperipheralwhileCPUisexecutingcode(no
cyclestealing)
?MostperipheralssupportDMA
DigitalI/O:
?Upto85programmabledigitalI/Opins
?Wake-up/Interrupt-on-Changeforupto24pins
?Outputpinscandrivevoltagefrom3.0Vto3.6V
?Upto5Voutputwithopendrainconfiguration
?5Vtolerantdigitalinputpins
?16mAsource/sinkonallPWMpins
On-ChipFlashandSRAM:
?Flashprogrammemory(upto64Kbytes)
?DataSRAM(upto8Kbytes)
?BootandGeneralSecurityforprogramFlash
PeripheralFeatures:
?Timer/Counters,uptofive16-bittimers
-Canpairuptomakeone32-bittimer
?InputCapture(uptofourchannels):
-Captureonup,downorbothedges
-16-bitcaptureinputfunctions
-4-deepFIFOoneachcapture
?OutputCompare(uptofourchannels):
-SingleorDual16-bitComparemode
-16-bitGlitchlessPWMmode
?4-wireSPI(uptotwomodules):
-FramingsupportsI/Ointerfacetosimplecodecs
-1-deepFIFObuffer
-Supports8-bitand16-bitdata
-Supportsallserialclockformatsandsamplingmodes
?I2C?(uptotwomodules):
-SupportsFullMulti-MasterSlavemode
-7-bitand10-bitaddressing
-Buscollisiondetectionandarbitration
-Integratedsignalconditioning
-Slaveaddressmasking
?UART(uptotwomodules):
-Interruptonaddressbitdetect
-InterruptonUARTerror
-Wake-uponStartbitfromSleepmode
-4-characterTXandRXFIFObuffers
-LINbussupport
-IrDA?encodinganddecodinginhardware
-High-SpeedBaudmode
-HardwareFlowControlwithCTSandRTS
?EnhancedCAN(ECAN?module)2.0Bactive:
-Uptoeighttransmitandupto32receivebuffers
-16receivefiltersandthreemasks
-Loopback,ListenOnlyandListenAll
-Messagesmodesfordiagnosticsandbusmonitoring
-Wake-uponCANmessage
-AutomaticprocessingofRemote
TransmissionRequests
-FIFOmodeusingDMA
-DeviceNet?addressingsupport
?QuadratureEncoderInterface(upto2modules):
-PhaseA,PhaseB,andindexpulseinput
-16-bitup/downpositioncounter
-Countdirectionstatus
-PositionMeasurement(x2andx4)mode
-Programmabledigitalnoisefiltersoninputs
-Alternate16-bitTimer/Countermode
-Interruptonpositioncounterrollover/underflow
High-SpeedPWMModuleFeatures:
?UptoninePWMgeneratorswithupto18outputs
?PrimaryandSecondarytime-base
?IndividualtimebaseanddutycycleforeachofthePWMoutput
?Deadtimeforrisingandfallingedges:
-Dutycycleresolutionof1.04ns
-Dead-timeresolutionof1.04ns
?Phaseshiftresolutionof1.04ns
?Frequencyresolutionof1.04ns
?PWMmodessupported:
-StandardEdge-Aligned
-TrueIndependentOutput
-Complementary
-Center-Aligned
-Push-Pull
-Multi-Phase
-VariablePhase
-FixedOff-Time
-CurrentReset
-Current-Limit
?IndependentFault/Current-Limitinputs
?Outputoverridecontrol
?SpecialEventTrigger
?PWMcapturefeature
?Prescalerforinputclock
?DualTriggerfromPWMTOADC
?PWMxL,PWMxHoutputpinswapping
?On-the-FlyPWMFrequency,DutycycleandPhaseShiftchanges
?DisablingofIndividualPWMgenerators
?Leading-EdgeBlanking(LEB)functionality
High-SpeedAnalogComparator:
?UptofourAnalogComparators:
-20nsresponsetime
-10-bitDACforeachanalogcomparator
-DACOUTpintoprovideDACoutput
-Programmableoutputpolarity
-Selectableinputsource
-ADCsampleandconvertcapability
?PWMmoduleinterface:
-PWMDutyCycleControl
-PWMPeriodControl
-PWMFaultDetect
InterruptController:
?5-cyclelatency
?Uptofiveexternalinterrupts
?Sevenprogrammableprioritylevels
?Fiveprocessorexceptions
High-Speed10-bitADC:
?10-bitresolution
?Upto24inputchannelsgroupedinto12conversionpairs
?Twointernalreferencemonitoringinputsgroupedintoapair
?SuccessiveApproximationRegister(SAR)convertersforparallelconversionsofanalogpairs:
-4MspsfordeviceswithtwoSARs
-2MspsfordeviceswithoneSAR
?Dedicatedresultbufferforeachanalogchannel
?Independenttriggersourcesectionforeachanaloginputconversionpairs
PowerManagement:
?On-chip2.5Vvoltageregulator
?Switchbetweenclocksourcesinrealtime
?Idle,Sleep,andDozemodeswith
CMOSFlashTechnology:
?Low-power,high-speedFlashtechnology
?Fullystaticdesign
?3.3V(±10%)operatingvoltage
?IndustrialandExtendedtemperature
?Lowpowerconsumption
SystemManagement:
?Flexibleclockoptions:
-External,crystal,resonator,internalRC
-Phase-LockedLoop(PLL)with120MHzVCO
-PrimaryCrystalOscillator(OSC)intherangeof3MHzto40MHz
-Secondaryoscillator(SOSC)
-InternalLow-PowerRC(LPRC)oscillatoratafrequencyof32.767kHz
-InternalFastRC(FRC)oscillatoratafrequencyof7.37MHz
?Power-onReset(POR)
?Brown-outReset(BOR)
?Power-upTimer(PWRT)
?OscillatorStart-upTimer(OST)
?WatchdogTimerwithitsRCoscillator
?Fail-SafeClockMonitor
?Resetbymultiplesources
?In-CircuitSerialProgramming?(ICSP?)
?ReferenceOscillatorOutput
ApplicationExamples:
?AC-to-DCConverters
?AutomotiveHID
?BatteryChargers
?DC-to-DCConverters
?DigitalLighting
?InductionCooking
?LEDBallast
?RenewablePower/PureSineWaveInverters
?UninterruptiblePowerSupply(UPS)
图1.dsPIC33系列方框图
图2.dsPIC33系列DSP引擎方框图
图3.dsPIC33推荐的最少连接方框图
图4.dsPIC33系列数字PFC方框图
图5.dsPIC33系列升压转换器实现方框图
图6.dsPIC33系列单相同步转换器方框图
图7.dsPIC33系列多相同步降压转换器方框图
图8.dsPIC33系列隔行扫描PFC方框图
图9.dsPIC33系列相移全桥转换器方框图
图10.带PFC和三输出(12V,5V和3.3V)的AC/DC电源电路图
Explorer16低成本高效开发板
TheExplorer16isalowcost,efficientdevelopmentboardtoevaluatethefeaturesandperformanceofMicrochip’snewPIC24Microcontroller,thedsPIC33DigitalSignalController(DSC)families,andthenew32-bitPIC32MXdevices.CoupledwiththeMPLABICD2InCircuitDebuggerorMPLABREALICE,real-timeemulationanddebugfacilitiesspeedevaluationandprototypingofapplicationcircuitry.TheExplorer16100-pinfeaturestwointerchangeablePlug-InModules(PIMs),oneeachforthePIC24FJ128GA010andthedsPIC33FJ256GP710DSC.TheExplorer1644-pinfeaturesaPlug-InModule(PIM)forthePIC24FJ64GA004.
Explorer16开发板主要特性:
?IncludesPIC24FJ128GA010andthedsPIC33FJ256GP710DSCDigitalSignalControllerPIMs(100-pinversion)orthePIC24FJ64GA004PIM(44-pinversion).
?Alpha-numeric16x2LCDdisplay
?InterfacestoMPLABICD2,MPLABREALICE,USB,andRS-232
?IncludesMicrochip’sTC1047Ahighaccuracy,analogoutputtemperaturesensor
?Expansionconnectortoaccessfulldevicespin-outandbreadboardprototypingarea
?PICTailTMPlusconnectorforexpansionboards
?FulldocumentationCDincludesuser’sguide,schematicsandPWBlayout
图11.Explorer16开发板外形图
图12.Explorer16开发板电路图(1)
图13.Explorer16开发板电路图(2)
图14.Explorer16开发板电路图(3)
图15.Explorer16开发板电路图(4)
图16.Explorer16开发板电路图(5)
图17.Explorer16开发板电路图(6)
详情请见:
http://ww1.microchip.com/downloads/en/DeviceDoc/70591C.pdf
和
http://ww1.microchip.com/downloads/en/DeviceDoc/DM240001%20BOM%20and%20Schematics.pdf，Marvell公司为88EM8081驱动芯片的这些Turn-key设计方案投入很大，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-couplerrequiredforoutputvoltagefeedbackintoasingle-stageconverter.ALT3798baseddesigncanachieveapowerfactorofgreaterthan0.97byactivELymodulatingtheinputcurrent,allowingcompliancewithmostHarmonicCurrentEmissionrequirements.
TheLT3798iswellsuitedforawidevarietyofoff-lineapplications.TheinputrangecanbescaLEDupordown,dependingmainlyonthechoiceofexternalcomponents.
Efficiencieshigherthan86%canbeachievedwithoutputpowerlevelsupto100watts.Inaddition,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1.LT3798方框图
图2.LT3798通用输入24WPFC总线电源电路图
图3.LT3798通用输入48WPFC电源电路图
，中艾电源LED投光灯外壳批发
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
iW3620：DigitalPWMConstantCurrentControllerforAC/DCLEDDriver
TheiW3620isahighperformanceAC/DCofflineLEDdriverwhichusesdigitalcontroltechnologytobuildpeakcurrentmodePWMflybackpowersupplies.Thedeviceoperatesinquasi-resonantmodeatheavyloadtoprovidehighefficiencyalongwithanumberofkeybuilt-inprotectionfeatureswhileminimizingtheexternalcomponentcount,simplifyingEMIdesignandloweringthetotalbillofmaterialcost.TheiW3620removestheneedforsecondaryfeedbackcircuitrywhileachievingexcELlentlineandloadregulation.Italsoeliminatestheneedforloopcompensationcomponentswhilemaintainingstabilityoveralloperatingconditions.Pulse-by-pulsewaveformanalysisallowsforaloopresponsethatismuchfasterthantraditionalsolutions,resultinginimproveddynamicloadresponse.Thebuilt-incurrentlimitfunctionenablesoptimizedtransformerdesigninuniversaloff-lineapplicationsoverawideinputvoltagerange.
iW3620主要特性：
Primary-sidefeedbackeliminatesopto-isolatorsandsimplifiesdesign
Quasi-resonantoperationforhighestoverallefficiencyandlowEMI
Upto130kHzswitchingfrequencyenablessmallsize
VerytightLEDconstantcurrentregulation
Built-inoutputconstant-currentcontrolwithprimary-sidefeedbackforLEDdriver.
Lowstart-upcurrent(10μAtypical)
Built-insoftstart
Built-inshortcircuitprotectionandoutputovervoltageprotection
Currentsenseresistorshortprotection
Over-temperatureProtection
Opencircuitprotection
Universalinputrangefrom85Vacto264Vac
Single-faultprotection
Smallinputbulkcapacitor
LongMTBF
Highefficiency
iW3620应用：
SolidStateLEDlightingforincandescent,halogen,andfluorescenttubereplacement
图1。iW3620典型应用电路
详情请见：
http://www.iwatt.com/pdf/iW3620.pdf
， ZMDI公司的Zled7022是六路低噪音恒定频率电荷泵DC/DC转换器,可驱动六路LED,每路LED的电流从1.8mA到20mA可编程,并联工作时可驱动更大电流的LED,工作电压2.8V-5.5V,关断模式电流小于2uA,主要用在手提设备的LED背光,手机,智能手机和PDA的LED照明,数码相框照明等.本文介绍了ZLED7022主要特性和`优势,方框图以及典型应用电路.
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
，深入探讨适合
分布式恒流就是：在各并联支路点均设立独立恒流源,从而管理、维持、控制支路与整体线路稳定。在使用上可视为一个完整的线路结构,而实际应用是分布在线路各节点的恒流控制并能相互通讯。分布式恒流设计LED产品,有着非常高的产品稳定性。在当前,LED产品宣称与实际使用寿命有较大的差距,在驱动线路设计技术积累有限的情况下,评估产品寿命与实际使用有距离。驱动线路稳定性直接影响产品整体稳定,分布式恒流有着独有的优势。
保持支路和整体电流稳定,还要能方便控制管理支路和整体线路工作,这是分布式恒流技术的包含范围。驱动LED需要恒流,但是电流的大小取决于应用环境,LED照明智能化发展是关键,分布式恒流技术充份预留智能化接口。
在分布式LED驱动设计中,驱动回搜、色温可调、灰度控制都要变得方便。这是分布式恒流技术发展的必要性,随温度变化驱动电压要适当调整,客户设计因产品而异LED数量不一,支路恒流平衡都需要回授线路完成。LED在迅速替代CCFL作为新一代背光源,但是我们发现显色性并没有CCFL好,色温也不能可调,不是我们不需要LED色温可调整,关键是设计线路不支持色温可调整。
在LED应用中,灰度也需要很好的表现,灰度控制总是会和亮度混淆,实际上有着本质的区别,灰度控制代表着智能化的水平程度,而亮度在产品中只设定一次,智能化一定离不了灰度等级再现。
分布式恒流技术还有一个特点是,让AC电源部分继续采用传统开关电源,恒压的供电模式。开关电源技术积累会给LED投光灯外壳设计创造品质条件,虽然加速老化估算电源寿命是一种办法,和传统开关电源长期实战技术积累还是有些差距!
分布式恒流也有它缺点,开始会增加部分设计成本,产品设计品质与线路设计选择需要权衡。可能成本增加是短暂的,表面的,应该综合考量。
2、分布式恒流源节点设置
分布式恒流技术就是在需要恒流的节点上串接,低压差线性恒流驱动器。低压差很重要,关系到产品驱动效率。做到恒流驱动有很多种,其中低压差线性恒流就可以实现一切LED应用设计,即稳定又简单,结合开关电源,有着完美的恒流驱动架构。
恒流源放置点灵活,在所有的并联支路,不会因支路电流变化影响其它支路工作。都希望挑选LED得到负载阻抗匹配,分布式恒流可以设计变得更完美,要求不是很高也可以免除挑选。保持各支路和整体线路电流稳定,才能提升灯具产品稳定性。
恒流源放置,在每个并联支路节点,也可以是整体的恒流点设计,恒流源串接支路中在某一个位置都能起到很好的作用。一般恒流驱动通道数很难与设计匹配,分布式恒流会有着高度的设计灵活性。
在LED照明线路设计中,AC电源需要回授电路,配合输出LED驱动数量,和驱动效率的合理性。在分布式恒流驱动源中,每一个驱动源都可以直接完成光耦回授任务。
3、恒流输出软件化将开辟,LED应用技术的飞跃
在日常驱动电源设计中,周边器件累计误差处理起来很是棘手,结果驱动电源参数离设计初衷相差甚远。恒流驱动需要电流检测,通常做法是在支路中串接毫偶电阻获取回授信息,要达到高的效率,电阻值会越小,过小的毫偶电阻给生产、测试都带来麻烦,一般的仪器无法验证到正确值,生产过程会影响到精度,电流值被固定,调整非常不便。
分布式恒流输出软件化将开辟,LED应用技术的飞跃,LED恒流技术软件化,大幅提升LED应用的灵活性。恒流驱动器电流设定软件化实际上也很简单,在IC内部设立寄存器,根据实际产品应用存储的方式设置输出电流大小,这一切都是软件化过程,不需要更改线路设计。在销售器件的同时附赠上微机操作软件,直观的数字写入完成电路电流设定。
驱动线路周边0器件,这是我们的目标,周边0器件不会带来设计器件参数误差累计,因周边器件误差累计而造成的恒流精度回升到0。
4、驱动优势
我们将恒流输出范围均等的划分若干等级,每阶电流被数字化描述,指定在一定空间内的寄存器,上电驱动IC会读取对应数字并执行相应电流值。内置E2PROM是首选,任何寄存器都能完成其任务,按照应用需要和工艺允许程度,决定存储器的类型选择。
在开发驱动技术的同时,也要同时开发应用软件,友好的界面支持数字化写入技术,使得LED驱动电源设计变得更简单,更智能。
电流阶划分与设计要求有所不同,因长运通公司型号对应市场不同有所区别。分布式恒流内置寄存器后,电流值划分会弥补工艺上的精度不足,因制造工艺原因输出电流总是有误差,因此得到改善。
驱动IC出厂时可以确定输出电流大小,可根据不同的客户,提供不同的电流输出值,免除批量校准过程。对于小客户来讲,通过附赠上微机软件改写电流值,是最为方便的方式。还有一种情况,也是客户经常需要的,比如对产品的亮度要求,允许驱动电流不同,要求产品亮度一致,从而通过产品设计接口解决终端客户对亮度的要求。在年久后,因LED光衰减或根据现实使用情况,再次确定驱动电流值及用途。
5、分布式接口
分布式恒流技术需要分布式通讯方式支持,LED智能化要有先进的通讯技术完成。单线数据传输,被选定为LED分布式技术通讯方式,采用曼彻斯特编码,固定速率400Kbps,通讯可靠传输距离大于1米,级联可达1024个恒流源,内置150℃温度保护,同时提供光耦驱动接口。
在分布式恒流技术中,每一颗独立的恒流源,都能完成光耦回授。根据恒流源压差信息,直接驱动光耦,完成电路回授过程。做到周边设计0器件,电源输出电压与负载阻抗匹配,实现恒流源与光源集成。
6、AC电源发展方向分析
1.原边反馈电源
用于小功率LED灯具驱动,采用原有原边反馈充电器开关电源移植而来。这部分AC驱动没有因LED应用而改变规格,有着诸多的型号供选择,除体积受限外设计上与开关电源没有本质区别,借来应用到LED也算合理。
2.大功率隔离照明电源
LED全部是采用开关电源而设计,任何公司到目前为止都没有推出针对LED专用AC驱动器件,隔离设计就是设计开关电源,LED产业热顺道说给LED开发而已,基本可以断言开关电源就是LED-AC驱动,也是主要的应用方式之一。
3.非隔离LED驱动电源
非隔离LED驱动推出较多针对性电源技术,是值得肯定的,是LED投光灯外壳一个方向。隔离安全主要取决于与外壳爬电间隙设计,并没有规定LED投光灯外壳一定要隔离设计,也没有限制输出电压值,关键是采用哪种隔离安全,非隔离有驱动效率高等优点,结合结构也能设计出优质、安全、高效的LED产品。
4.可控硅调光兼容性电源
特殊应用,数量受限,有过渡性安排。
最后总结!
这几年我们主张《先恒压,再恒流》,会是LED照明市场主流,经过这两年的发展严谨的定义为《分布式恒流》技术。虽然各大公司,诸多的专家学者在致力于《LED照明电源》研究,我们依然看到的还是开关电源而已!为此LED照明电源主要研究的重点应该放在：次级DC部分,恒压开关电源与分布式恒流技术结合。
，Analogic公司的AAT1451是四路高集成高效白光LED驱动器,主要用于笔记本电脑,上网本,监视器和手提TV的LCD背光的LED驱动.器件的输入电压从5V到26V,可从DC,点烟适配器或多个锂电池输入,集成的升压转换器提供高达50V的输出,每串led电流高达30mA可编程,120mA总输出电流可驱动多达481个LED.效率高达93%,主要用在监视器,笔记本和上网本电脑,手提DVD播放器,手提TV和白光LED背光.本文介绍了AAT1451主要特性,方框图,典型应用电路图以及评估板电路图和材料清单,PCB布局图.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
，。