由于省去了接线焊接的二级加工过程，全新的低边LED驱动器BCR321U和BCR421U是最理想的选择。利用BCR321U可调节高达250mA的电流。这两种型号的驱动器都具备一个直接逻辑电平输入端， Cypress公司的CY8CledAC02是高性能离线LED驱动器,AC离线输入从80V到277VAC,输出功率高达25W,调光效率从2%到100%,主要用在可调光的离线LED驱动器,LED替代灯以及LED照明.本文介绍CY8CLEDAC02主要特性,方框图,简化和典型的应用电路图,以及采用CY8CLEDAC02的220VAC17W可调光LED驱动器参考设计系统指标,电路图,材料清单和变压器指标.
TheCY8CLEDAC02isahighperformanceofflineLEDdriver,designedtointerfacedirectlywithmostconventionalphasecutbasedwalldimmers.Thedeviceusesproprietarydigitalcontroltechnologytoprovideautomaticdetectionofdimmertype
(leadingortrailingedge).ItautomaticallygeneratesdimmingsignalsforLEDloadsandhastheabilitytodimdownto2%.ItmodulatesLEDbrightnessusingalineardimmingschemeandswitchestoaPWMbaseddimmingschemeforoutputcurrentlevELslowerthan20%ofthefullloadcurrent.InPWMmodeoptimizeddimmingfrequenciesintherangeof900Hzresultinzerovisibleflicker.
AttheheartofaCY8CLEDAC02basedsystemisthechoppingcircuitwhichprovidestheloadnecessarytoenablecorrectwalldimmeroperation.ItalsoimprovesPFwhenthereisnodimmerontheline.
Thedevices’proprietaryprimarysidesensingenablestightLEDcurrentregulationandeliminatestheneedforsecondaryfeedbackcircuitry.Noopto-couplersarenecessarytomeetULisolationrequirements;enablingflybackconversionwithautomaticisolation.
TheCY8CLEDAC02operatesinquasi-resonantmodetoachievehighefficiency.ThismodeofoperationhelpsminimizeexternalcomponentcountandsimplifiesEMIdesign,loweringthetotalbillofmaterialcost.
Thedevice’scycle-by-cycleadaptivedigitalregulationusescriticaldiscontinuousconductionmode(CDCM)whendrivingLEDloads.Thecontrolalgorithmforcycle-by-cycleregulationhasinternalcompensationforguaranteedsystemphaseandgainmargins;requiringnoexternalcomponentsforloopcompensation.
TheCY8CLEDAC02hasfullfeaturedcircuitprotectionnotnormallyavailablewithotherprimary-sidecontrolsolutions.Thebuilt-inprotectionincludesoutputovervoltageprotection(OOVP),outputshortcircuitprotection(OSCP),overtemperatureprotection(OTP),current-senseresistorshortprotection(CSSP),andpeakcurrentlimitprotection(PCLP).ItalsoenablesautomaticLEDbrightnessadjustmenttocompensatefortemperaturedriftbysimplyconnectingaNTCresistortotheVTpin.
CY8CLEDAC02主要特性:
■ACofflineinputrangefrom80to277VAC
■Upto25Woutputpowerrange
■Intelligentwalldimmerdetection:
?Leadingedge(R,RL)dimmers
?Trailingedge(RC,RLC)dimmers
?Nodimmer
■Widedimmingrangefrom2to100%
■Resonantcontroltoachievehighefficiency(85%withoutdimmer)
■Meetsharmonicrequirementwithhighpowerfactor(0.7withoutdimmer)
■Primary-sidesensingeliminatesopto-isolators
■TightLEDcurrentregulation(typically<+2.5%)
■Lowstartupcurrent(typically10??A)
■Lowstartuptime(typically0.5swithactivestartup)
■Multipleprotectionfeatures:
?Outputovervoltageprotection(OOVP)
?Outputshortcircuitprotection(OSCP)
?Overtemperatureprotection(OTP)
?Current-senseresistorshortprotection(CSSP)
?Peakcurrentlimitprotection(PCLP)
?Single-pointfaultprotection
CY8CLEDAC02应用:
?DimmableofflineLEDdriver
?DimmableLEDreplacementlamps
?DimmableLEDluminaires
图1.CY8CLEDAC02逻辑方框图
图2.CY8CLEDAC02简化应用电路图
图3.CY8CLEDAC02典型应用电路图
采用CY8CLEDAC02的17W调光LED驱动器参考设计
HighLine17WDimmableLEDDriverusingCY8CLEDAC02ReferenceDesignGuide
Thisdocumentdescribesa17WdimmableLEDdriverreferencedesignusingtheCY8CLEDAC02AC-DCpowercontrollerdevice.ThisreferencedesigniscapableofdrivingeightwhiteLEDs(typicalloadvoltageof25V)at530mA.
TheCY8CLEDAC02isahighperformanceofflineLEDdriver,designedtointerfacedirectlywithmostconventionalphasecutbasedwalldimmers.Thedeviceusesproprietarydigitalcontroltechnologytoprovideautomaticdetectionofdimmertype(leadingortrailingedge).ItautomaticallygeneratesdimmingsignalsforLEDloadsandhastheabilitytodimdownto2%.
参考设计系统指标:
图4.17W调光LED驱动器参考设计外形图
图5.17W调光LED驱动器参考设计电路图
17W调光LED驱动器参考设计材料清单(BOM):
变压器指标:
ThetransformerisoneofthemostimportantcomponentsinthisLEDdrivercircuit.Asexplainedinprevioussections,inadditiontothetwostandardwindings,typicalflybackconvertertransformersincorporateathirdwinding.Inthiscircuit,itisusedtoprovidevoltagesensingforoutputvoltageregulationandno-loadprotectionbytheCY8CLEDAC02device.Thiswinding,calledthebiasorauxiliarywinding,alsoprovidessupplyvoltage(VCC)totheCY8CLEDAC02.
Thespecificationsofthetransformerforthisreferencedesignareasfollows:
Electricalspecifications
Primaryinductance=1200μHat10kHz
Primaryleakageinductance≤20μHat10kHz
Materials
Core:EF2011(FerritematerialTDKPC40orequivalent)
Bobbin:EF2011
Magnetwires:Type2UEW
Layerinsulationtape:3M1298orequivalent
，N为串联的LED个数。Vnm为LED正向压降。f为振荡频率。L1为限流电感器的电感。
led高节能：节能能源无污染即为环保。直流驱动，
Allegro公司的A8735是超低功耗Xenon闪光灯充电集成电路,封装尺寸只有2x2mm,关断模式的电流仅为0.5uA,峰值电流1A限制,效率大于75%,很适合用于手机单个锂离子电池充电以及小型照相机.本文介绍了A8735主要特性和优势,功能方框图,典型应用电路图以及推荐的PCB布局图.
TheAllegro?A8735isaXenonphotoflashchargerICdesignedtomeettheneedsofultralowpower,smallformfactorcameras,particularlycameraphones.Byusingprimary-sidevoltagesensing,theneedforasecondary-sideresistivevoltagedividerisELiminated.Thishastheadditionalbenefitofreducingleakagecurrentsonthesecondarysideofthetransformer.Toextendbatterylife,theA8735featuresverylowsupplycurrentdraw(0.5μAmaxinshutdownmode).TheIGBTdriveralsohasinternalgateresistorsforminimumexternalcomponentcount.Thechargeandtriggervoltagelogicthresholdsaresetat1VHI(min)tosupportapplicationsimplementinglow-voltagecontrollogic.
TheA8735isavailableinan8-contact2mm×2mmDFN/MLPpackagewitha0.60maximumoverallpackageheight,andanexposedpadforenhancedthermalperformance.Itislead(Pb)freewith100%mattetinleadframeplating.
A8735主要特性和优势:
?Ultrasmall2×2DFN/MLP-8package
?Lowquiescentcurrentdraw(0.5μAmax.inshutdownmode)
?Primary-sideoutputvoltagesensing;noresistordividerrequired
?Fixed1Apeakcurrentlimit
?1Vlogic(VHI(min))compatibility
?IntegratedIGBTdriverwithinternalgateresistors
?Optimizedformobilephone,1-cellLi+batteryapplications
?Zero-voltageswitchingforlowerloss
?>75%efficiency
?Chargecompleteindication
?Integrated50VDMOSswitchwithself-clampingprotection
图1.A8735功能方框图
图2.A8735单电源应用电路图
图3.A8735带单独偏压电源的应用电路图
图4.A8735推荐的应用电路图
图5.A8735推荐的元件布局图
详情请见:
http://www.allegromicro.com/en/Products/Part_Numbers/8735/8735.pdf
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