AN_SY8291_TSR_Vinson

ApplicationNote:AN_SY8291HighEfficiency,800kHz,40VInput,1.2AAsynchronousStepDownRegulatorAN_SY8291Rev.0.9CSilergyCorp.Confidential-PreparedforCustomerUseOnly1GeneralDescriptionTheSY8291isahighefficiency800kHz,adaptiveconstantOFFtimecontrolledasynchronousstep-downDC-DCregulatorcapableofdelivering1.2Aoutputcurrentrespectively.TheSY8291canoperateoverawideinputvoltagerangefrom5Vto40VandintegratethemainswitchwithverylowRDS(ON)tominimizetheconductionloss.Lowoutputvoltagerippleandsmallexternalinductorandcapacitorsizesareachievedwith800kHzswitchingfrequency.OrderingInformationPackageCodeTemperatureCodeOptionalSpecCode□□□□(□□□□□□□□)□□□□PackageCodeTemperatureCodeOptionalSpecCode□□□□(□□□□□□□□)□□□□SY8291Features•5-40Vinputvoltagerange•LowRDS(ON)forinternalN-channelPowerFET:180mΩ•800kHzswitchingfrequency•AdaptiveconstantOFFtimecontrol•Internalsoftstartlimitstheinrushcurrent•2%0.6Vreference•RoHSCompliantandHalogenFree•Compactpackage:SOT23-6Applications•SetTopBox•PortableTV•AccessPointRouter•DSLModem•LCDTVTypicalApplicationsLXINGNDFBENBSL10uHDCOUT22uFVOUT=5VVINCIN2.2uFOFF/ONCBS100nFR1100kΩR213.7kΩCFF47pFFigure1.SchematicDiagramFigure2.EfficiencyFigureOrderingNumberPackagetypeNoteSY8291ABCSOT23-6--SilergyCorp.Confidential-PreparedforTSRAN_SY8291AN_SY8291Rev.0.9CSilergyCorp.Confidential-PreparedforCustomerUseOnly2Pinout(topview)BSGNDFBLXINEN123654(SOT23-6)TopMark:YMxyz(Devicecode:YM,x=yearcode,y=weekcode,z=lotnumbercode)PinNamePinNumberPinDescriptionBS1Boot-StrapPin.Supplyhighsidegatedriver.DecouplethispintoLXpinwith0.1uFceramiccap.GND2GroundpinFB3OutputFeedbackPin.Connectthispintothecenterpointoftheoutputresistordivider(asshowninFigure1)toprogramtheoutputvoltage:VOUT=0.6*(1+R1/R2)EN4Enablecontrol.Pullhightoturnon.Donotfloat.IN5Inputpin.DecouplethispintoGNDpinwithatleast2.2uFceramiccapLX6Inductorpin.ConnectthispintotheswitchingnodeofinductorAbsoluteMaximumRatings(Note1)SupplyInputVoltage-----------------------------------------------------------------------------------------------------------42VEnableVoltage-----------------------------------------------------------------------------------------------------------VIN+0.6VFBVoltage----------------------------------------------------------------------------------------------------------------------3.6VBStoLXVoltage--------------------------------------------------------------------------------------------------------------3.6VPowerDissipation,PD@TA=25°C,SOT23-6--------------------------------------------------------------------------0.6WPackageThermalResistance(Note2)θJA--------------------------------------------------------------------------------------------------------------170°C/WθJC--------------------------------------------------------------------------------------------------------------130°C/WJunctionTemperatureRange-----------------------------------------------------------------------------------------------150°CLeadTemperature(Soldering,10sec.)-----------------------------------------------------------------------------------260°CStorageTemperatureRange--------------------------------------------------------------------------------------65°Cto150°CRecommendedOperatingConditions(Note3)SupplyInputVoltage--------------------------------------------------------------------------------------------------5Vto40VBStoLXVoltage---------------------------------------------------------------------------------------------------------------3.3VJunctionTemperatureRange--------------------------------------------------------------------------------------40°Cto125°CAmbientTemperatureRange---------------------------------------------------------------------------------------40°Cto85°CSilergyCorp.Confidential-PreparedforTSRAN_SY8291AN_SY8291Rev.0.9CSilergyCorp.Confidential-PreparedforCustomerUseOnly3ElectricalCharacteristics(VIN=12V,VOUT=5V,L=10uH,COUT=22uF,TA=25°C,IOUT=0.5Aunlessotherwisespecified)ParameterSymbolTestConditionsMinTypMaxUnitInputVoltageRangeVIN540VInputUVLOThresholdVUVLORising4.5VInputUVLOThresholdFalling4.3VInputUVLOHysteresisVUVLO_HYS200mVQuiescentCurrentIQIOUT=0,VFB=VREF×105%160µAShutdownCurrentISHDNEN=010µAFeedbackReferenceVoltageVREF0.5880.60.612VFBInputCurrentIFBVFB=VIN-5050nAPowerFETRONRDS(ON)1180mΩPowerFETCurrentLimitILIMVFB=VREF×98%1.62AENRisingThresholdVENH1.5VENFallingThresholdVENL0.4VMinimumOFFTimeTOFF100nsMinimumONTimeTOFF100nsMaximumONTimeTON2usOscillatorFrequencyFOSC800kHzThermalShutdownTemperatureTSD150°CThermalShutdownRecoveryHysteresisTHYS15°CNote1:Stressesbeyondthe“AbsoluteMaximumRatings”maycausepermanentdamagetothedevice.Thesearestressratingsonly.Functionaloperationofthedeviceattheseoranyotherconditionsbeyondthoseindicatedintheoperationalsectionsofthespecificationisnotimplied.Exposuretoabsolutemaximumratingconditionsforextendedperiodsmayaffectdevicereliability.Note2:θJAismeasuredinthenaturalconvectionatTA=25°ConaloweffectivesinglelayerthermalconductivitytestboardofJEDEC51-3thermalmeasurementstandard.Note3:Thedeviceisnotguaranteedtofunctionoutsidei