PAM2803-Rev10 工作原理图及规格书.pdf

FeaturesLED Power Efficiency:up to 90%Current Accuracy:5%(V=3.6V to 1.8VV=3.7V)1MHz Switching FrequencyUses small,Low Profile External ComponentsLow RDS(ON):100m(TYP.)Open LED ProtectionOver Temperature ProtectionLow Profile SOT-23-6 PackagePb-Free PackageINFLow Start-Up Voltage:0.9V(I=270mA)Low Hold Voltage:0.75V(I=200mA)White LED Torch(Flashlight)White LED Camera FlashDSC(Digital Still Camera)FlashCellular Camera Phone FlashPDA Camera FlashCamcorder Torch(Flashlight)LampThe PAM2803 is a set-up DC-DC converter thatdelivers a regulated output current.The deviceswitchesata1.0MHzconstantfrequency,allowingfortheuseofsmallvalueexternalinductor and ceramic capacitors.The PAM2803 is targeted to be used for drivingloads up to 1A from a two-cell alkaline battery.TheLED current can be programmed by the externalcurrent sense resistor,Rs,connected between thefeedbackpin(FB)andground.A low95mVfeedback voltage reduces the power loss in the Rsfor better efficiency.With its internal 2A,100devicecanprovidehighefficiencyevenatheavyload.Duringtheshutdown mode,the feedback resistor Rs and theload are completely disconnected and the currentconsumption is reduced to less than 1uA.The PAM2803 is available in the 6-lead SOT-23-6package.LEDLEDApplicationsGeneral DescriptionmNMOSswitch,the?Typical Application95mVReference+A1-RcCc-A2+ComparatorVOUTVINSWPWM LogicAnd Driver+-GND1.0MHzOscillatorShutdownAndSoft-startFBRampGeneratorSHDNBlock D08/2007PAM28033W High Power White LED Driver10uF2.2uH10uFOFF ONRS321654SWVINVOUTFBSHDNGNDWLEDVINCOCIN3WPAM2803I=750mA,R=0.127LEDS,Power Analog Microelectronics Inc PAM原厂指定 代理商龙创威电子2012-03-12联系-13590496412 吴RPin Configuration&Marking InformationTop ViewSOT 23 6-XX V Y WXX V Y W1236542Pin NumberNameFunction1SWSwitch2GNDGround3FBFeedback4SHDNShut Down5VOUTOutput6VINInputAbsolute Maximum RatingsThesearestressratingsonlyandfunctionaloperationisnotimpliedExposuretoabsolutemaximum ratings for prolonged time periods may affect device reliabilityAll voltages are withrespect to ground.Input Pin Voltage.0.3V to 6VSW Pin Voltage.0.3V to 6VSHDN,FB Pin Voltage.0.3V to 6VOperating Temperature Range.-40 C to 85 CStorage Temperature Range.65 C to 125 CLead Temperature(Soldering,5 sec).300 C?Recommended Operating ConditionsJunction Temperature40to 125-.CC.CC?Ambient Temperature40to 85-Thermal InformationParameterPackageSymbolMaximumUnitThermal Resistance(Junction to Case)SOT-23-6JC130Thermal Resistance(Junction to Ambient)SOT-23-6JA250/WInternal Power DissipationSOT-23-6PD400mWXX:Product CodeV:Voltage CodeY:YearW:Weekly08/2007PAM28033W High Power White LED Driver,Power Analog Microelectronics I3Electrical CharacteristicT=25,V=2.4V,I=750mA,V=V,L=2.2uH,C=10uF,C=10uF,unless otherwise noted.AINLEDSHDNINONote1:V-LED Forward VoltageF08/2007PAM28033W High Power White LED DriverParameterSymbolConditionsMinTypMaxUnitInput Voltage RangeVIN0.9VF-0.2(note 1)VFeedback VoltageVFB9095100mVStart-up VoltageVSTARTVIN:0V3VILED=270mA0.9VHold VoltageVHOLDVIN:3V0VILED:750mA200mA0.75VOscillator FrequencyFOSC0.851.01.15MHzSHDN Input HighVSHVIN=1.8V1.0VSHDN Input LowVSLVIN=1.8V0.4VOver Temperature ShutdownOTS150Over Temperature HysteresisOTH15Maximum Output CurrentRangeIO(MAX)750mAQuiescent CurrentIQILED=0mA,VO=3.4V,Device Switching at 1MHz13mAShutdown CurrentISDShutdown mode1uASwitch on ResistanceRDSONVO=3.4V0.1Current LimitILIMVO=3.4V2AEfficiencyILED=750mA90%,Power Analog Microelectronics ITypical Performance CharacteristicsT=25,L=2.2uH,C=10uF,C=10uF,unless otherwise noted.A408/2007PAM28033W High Power White LED Driver4004505005506006507007508001.21.51.82.12.42.733.33.6Input Voltage(V)LED Current(mA)ILED=750mAVF=3.7V505560657075808590951001.21.51.82.12.42.733.33.6Input Voltage(V)Feedback Voltage(mV)50070090011001300150017001900210023001.21.51.82.12.42.733.33.6Input Voltage(V)DC Input Current(mA)ILED=750mAVF=3.7V1.LED Power Efficiency vs Input Voltage2.LED Current vs Input Voltage3.DC Input Current vs Input Voltage4.Feedback Voltage vs Input Voltage(I=750mAV=3.7V)LEDF4050607080901001.21.51.82.12.42.733.33.6Input Voltage(V)LED Power Efficiency(%)ILED=750mAVF=3.7V,Power Analog Microelectronics ITypical Performance Characteristics(continued)57.Overvoltage Protection08/2007PAM28033W High Power White LED DriverSWVACCouplingOIL5.Switching Waveform6.Start-Up WaveformSHDNILVO,Power Analog Microelectronics IInductor SelectionCapacitor SelectionDiode SelectionLED Current SettingThe PAM2803 can use small value inductors dueto its switching frequency of 1 MHz.The value ofinductor will focus in the range of 2.2uH to 4.7uHfor most PAM2803 applications.In typical highcurrentwhiteLEDapplications,itisrecommended to use a 4.7uH inductor.Theinductor should have low DCR(DC resistance)tominimize the I R power loss,and it requires acurrent rating of 2A to handle the peak inductorcurrent without saturating.An input capacitor is required to reduce the inputripple and noise for proper operation of thePAM2803.For good input decoupling,Low ESR(equivalent series resistance)capacitors shouldbeusedattheinput.Atleast2.2uFinputcapacitor is recommended for most applications.A minimum output capacitor value of 6.8uF isrecommendedundernormaloperatingconditions,while a 10uF-22uF capacitor may berequiredforhigherpowerLEDcurrent.Areasonablevalueoftheoutputcapacitordepends on the LED current.The ESR of theoutput capacitor is the important parameter todeterminetheoutputvoltagerippleoftheconverter,so low ESR capacitors should be usedat the output to reduce the output voltage ripple.Thesmallsizeofceramiccapacitorsisanexcellent choice for PAM2803 applications.TheX5R and X7R types are preferred because theymaintain capacitance over wide voltage andtemperature ranges.Its indispensable to use a Schottky diode ratedat 2A with the PAM2803.Using a Schottky diodewith a lower forward voltage drop is better toimprove the power LED efficiency,and its voltagerating should be greater than the output voltage.Inapplication,theONSemiconductorMBRA210LT3G is recommended.The LED current is set by the single external Rsresistor connected to the FB pin as shown in thetypical application circuit on page 1.The typicalFB reference is internally regulated to 95mV.TheLED current is 95mV/Rs.Its recommended touse a 1%or better precision resistor for thebetter LED current accuracy.The formula andtable 1 for Rs selection are shown as follows:Rs=95mV/ITable 1.Rs Resistor Value Selection2LEDPCB Layout GuidelinesAs for all switching power supplies,the layoutand components placement of the PAM2803 isan important step in the design;especially athighpeakcurrentsandhighswitchingfrequencies.The input capacitor and output capacitor shouldbe placed respectively as close as possible tothe input pin and output pin of the IC;the inductorand schottky diode should be placed as close aspossible to the switch pin by using wide and shorttraces for the main current path;the currentsense resistor should be placed as close aspossible between the ground pin and feedbackpin.Application Information608/2007PAM28033W High Power White LED DriverStandard Value()ILED(mA)0.185280.156330.127920.10950,Power Analog Microelectronics IOrdering InformationPlease consult PAM sales office or authorized RepDistributor for detailed ordering information./7FB VoltageNumber of PinsPackage TypePin ConfigurationPAM2803 X X X X08/2007PAM28033W High Power White LED DriverPin ConfigurationPackage TypeNumber of PinsFB VoltageAType1.SW2.GND3.FB4.SHDN5.VOUT6.VINA:SOT-23-6F:6095：95mVPart NumberMarkingPackage TypeStandard PackagePAM2803AAF095CFAYWSOT-23-63,000Units/Tape&Reel,Power Analog Microelectronics IOutline DimensionSOT 23 6-SOT 23 6-GAUGE PLANESEATING PLANEGAUGE PLANESEATING PLANEVIEW BVIEW BL1L0.25L1L0.25WITH PLANTINGWITH PLANTINGBASE METALBASE METALA1A2AA1A2ASECTION A-ASECTION A-AcbcbSEE VIEWSSEE VIEWSAAe1eEE1AAe1eEE1SymbolAA1A2bcDESpec1.200.250.100.051.100.20.400.10.150.0.72.900.12.800.2SymbolE11ee 1LL1Spec1.600.10.95BSC1.90BSC0.550.250.60REF44808/2007PAM28033W High Power White LED Driver,Power Analog Microelectronics I