B628六脚升压IC-PL2628

1PuLanTechnologyFEATURES•Integrated80mΩPowerMOSFET•2Vto24VInputVoltage•1.2MHzFixedSwitchingFrequency•Internal4ASwitchCurrentLimit•AdjustableOutputVoltage•InternalCompensation•Upto28VOutputVoltage•AutomaticPulseFrequencyModulationModeatLightLoads•upto97%Efficiency•Availableina6-PinSOT23-6PackageAPPLICATIONS•Battery-PoweredEquipment•Set-TopBoxed•LCDBaisSupply•DSLandCableModemsandRouters•NetworkingcardspoweredfromPCIorPCIexpressslotsThePL2628isaconstantfrequency,6-pinSOT23currentmodestep-upconverterintendedforsmall,lowpowerapplications.ThePL2628switchesat1.2MHzandallowstheuseoftiny,lowcostcapacitorsandinductors2mmorlessinheight.Internalsoft-startresultsinsmallinrushcurrentandextendsbatterylife.ThePL2628featuresautomaticshiftingtopulsefrequencymodulationmodeatlightloads.ThePL2628includesunder-voltagelockout,currentlimiting,andthermaloverloadprotectiontopreventdamageintheeventofanoutputoverload.ThePL2628isavailableinasmall6-pinSOT-23package.GENERALDESCRIPTIONPACKAGE/ORDERINFORMATIONPL2628PL2628PULANTECHNOLOGYCO.,LIMITEDIN,ENvoltages………..….……-0.3Vto26VOperatingTemperature…....-40°Cto+85°CFBVoltages................................-0.3Vto6VJunctionTemperature………………...160°CSWVoltage……………………..-0.3Vto30VStorageTemperatureRange-65°Cto150°CPeakSWSinkandSourceCurrent………4ALeadTemperature(Soldering,10s)...+300°CPINDESCRIPTIONPINNAMEFUNCTION1SWPowerSwitchOutput.SWisthedrainoftheinternalMOSFETswitch.ConnectthepowerinductorandoutputrectifiertoSW.SWcanswingbetweenGNDand28V.2GNDGroundPin3FBFeedbackInput.TheFBvoltageis0.6V.ConnectaresistordividertoFB.4ENRegulatorOn/OffControlInput.AhighinputatENturnsontheconverter,andalowinputturnsitoff.Whennotused,connectENtotheinputsupplyforautomaticstartup.5INInputSupplyPin.Mustbelocallybypassed.6NCNCABSOLUTEMAXIMUMRATINGS2TYPICALAPPLICATIONFigure1.BasicApplicationCircuitEfficiencyIout(mA)Figure2.EfficiencyCurveEfficiency(%)PL2628PuLanTechnologyPULANTECHNOLOGYCO.,LIMITEDELECTRICALCHARACTERISTICS(VIN=VEN=5V,TA=25°C,unlessotherwisenoted.)ParameterConditionsMINTYPMAXunitOperatingInputVoltage224VUnderVoltageLockout1.98VUnderVoltageLockoutHysteresis100mVCurrent(Shutdown)VEN=0V0.11µAQuiescentCurrent(PFM)VFB=0.7V，Noswitch100200µAQuiescentCurrent(PWM)VFB=0.5V，switch1.62.2mASwitchingFrequency1.2MHzMaximumDutyCycleVFB=0V90%ENInputHighVoltage1.5VENInputLowVoltage0.4VFBVoltage0.5880.60.612VFBInputBiasCurrentVFB=0.6V-50-10nASWOnResistance(1)80150mΩSWCurrentLimit(1)VIN=5V,Dutycycle=50%4ASWLeakageVSW=20V1μAThermalShutdown155℃Note:1)Guaranteedbydesign,nottested.3PuLanTechnologyPL2628PULANTECHNOLOGYCO.,LIMITEDThePL2628usesafixedfrequency,peakcurrentmodeboostregulatorarchitecturetoregulatevoltageatthefeedbackpin.TheoperationofthePL2628canbeunderstoodbyreferringtotheblockdiagramofFigure3.AtthestartofeachoscillatorcycletheMOSFETisturnedonthroughthecontrolcircuitry.Topreventsub-harmonicoscillationsatdutycyclesgreaterthan50percent,astabilizingrampisaddedtotheoutputofthecurrentsenseamplifierandtheresultisfedintothenegativeinputofthePWMcomparator.WhenthisvoltageequalsTheoutputvoltageoftheerroramplifierthepowerMOSFETisturnedoff.Thevoltageattheoutputoftheerroramplifierisanamplifiedversionofthedifferencebetweenthe0.6Vbandgapreferencevoltageandthefeedbackvoltage.Inthiswaythepeakcurrentlevelkeepstheoutputinregulation.Ifthefeedbackvoltagestartstodrop,theoutputoftheerroramplifierincreases.TheseresultsinmorecurrenttoflowthroughthepowerMOSFET,thusincreasingthepowerdeliveredtotheoutput.ThePL2628hasinternalsoftstarttolimittheamountofinputcurrentatstartupandtoalsolimittheamountofovershootontheoutput.Figure3.FunctionalBlockDiagramOPERATION4PuLanTechnologyPL2628PULANTECHNOLOGYCO.,LIMITEDTYPICALOPERATINGCHARACTERISTICSEfficiencyCurveIout(mA)lineRegulationVin(V)FreqVSVinEfficiencyCurveIout(mA)LoadregualationIout(mA)EfficiencyVSVinEfficiencyVout(V)Currentlimit(A)Vout(V)5PuLanTechnologyPL2628PULANTECHNOLOGYCO.,LIMITEDSettingtheOutputVoltageTheinternalreferenceVREFis0.6V(Typical).Theoutputvoltageisdividedbyaresistordivider,R1andR2totheFBpin.Theoutputvoltageisgivenby)1(21RRVVREFOUT+×=InductorSelectionTherecommendedvaluesofinductorare4.7to22μH.Smallsizeandbetterefficiencyarethemajorconcernsforportabledevice,suchasPL2628usedformobilephone.Theinductorshouldhavelowcorelossat1.2MHzandlowDCRforbetterefficiency.Toavoidinductorsaturationcurrentratingshouldbeconsidered.CapacitorSelectionInputandoutputceramiccapacitorsof22μFarerecommendedforPL2628applications.Forbettervoltagefiltering,ceramiccapacitorswithlowESRarerecommended.X5RandX7Rtypesaresuitablebecauseoftheirwidervoltageandtemperatureranges.DiodeSelectionSchottkydiodeisagoodchoiceforPL2628becauseofitslowforwardvoltagedropandfastreversesrecovery.UsingSchottkydiodecangetbetterefficiency.ThehighspeedrectificationisalsoagoodcharacteristicofSchottkydiodeforhighswitchingfrequency.Currentratingofthediodemustmeettherootmeansquareofthepeakcurrentandoutputaveragecurrentmultiplicationasfollowing:PEAKOUTDIIRMSI×≈)(Thediode’sreversebreakdownvoltageshouldbelargerthantheoutputvoltage.LayoutConsiderationF