MOSFET损耗的计算

Notes:DieTempfunctionTabsDefinitionsEfficiencyChartLossChartControllerDriverMOSFETDatabaseEfficiencySummaryOutputCellsarecolorcodedasfollows:BesuretoturnoffMacroProtectioninExceltoallowthecustomfunctionsandmacrosinthissheettorun.ForExcel2000,thisisdonethroughTools|Macro|Security.Settheleveltolow.InExcel97,youcandothisthroughTools|Options.IntheGeneraltab,theMacroVirusProtectionboxshouldnotbechecked.RDS(ON)isafunctionofdietemperature,andthedietemperatureisafunctionofPowerDissipationwhichisinturndependentonRDS(ON).Tosolvefordissipationordietemperature,theconductionlosscalculationsinthisspreadsheetuseaniterativecalculationmethodtoarriveatthedietemperatureanddissipation.Function/DescriptionProvidesguidanceonwhatMOSFETparametricdatatoenterintheMOSFETDatabasetab.ThissheetisahotlinkdestinationfromsomeofthecolumnheadingsintheMOSFETDatabasetable.PlotsefficiencydatafromthetableinEfficiencySummarytab.PlotspowerlossdatafromthetableinEfficiencySummarytab.DatabasefortheICControllers.Fairchild'sportablePWMcontrollersarefeaturedinthisdatabase.AnycontrollercanbeaddedbyusingtheAddbuttonandfillingintheappropriatefields.DatabasefortheMOSFETs.ManypopularFairchildMOSFETsarefeaturedinthisdatabase.AnyMOSFETcanbeaddedbyusingtheAddbuttonandfillingintheappropriatefields.ThemainsheetwherethesystemrequirementsandMOSFETchoicescanbeentered,andthedataisstoredforgraphing.Torunthegraphingroutine,pushtheRUNbuttonatthetopofthesheet.ThecalculationscontainedintheSynchronousbuckMOSFETlosscalculationsappnoteareprogrammedintothissheet.TheEfficiencySummarymacrousesthissheetasitscalculator.Ifaparticularoperatingpointneedstobeexaminedinmoredetail,thenusethissheet,andentertheparametersbyhand.BesuretosaveacopyofthisworkbookbeforeoverwritingformulasinOutputtab.IndicatesuserinputparametersIndicatescalculatedvaluesthatcanbeoverwrittenwithselectedvaluesifdesired.Thesefieldsdefaulttothecalculatedvaluedirectlyabovethem.Thesefieldsarewritteninto,orcontainformulaethatwereinputontheEfficiencySummarysheet.Cellsarecolorcodedasfollows:DefinitionsfordatabaseentriesVSPistheVGSvoltagewheretheVDSchanges.Thisisreadilyidentifiedbytheflatportionofthegatechargecurve.Intheexamplecurvetotheright,VSPisabout2.8V.QG(SW)canbetakenfromthegraphasthedifferencebetweentheendoftheflatportion(about8nCintheexampletotheright)andtheQGvalueatVTH(about2.5nConthisgraph).Ifthegraphisnotavailable,agoodestimateisQGD+0.5*QGS.CISSisusedforlow-sideMOSFETswitchinglosscalculations.TheVDSofthelowsideMOSFETisat0whentheMOSFETisswitching.Therefore,usethevalueatwhichtheCISScurvecrosses0,whichistypicallyabout1.4xthedatasheettypicalvalue.CRSSisusedtocalculatethelow-sidegatestepwhichiscausedbytheSWnoderiseinjectingchargethroughCGD.Usedatasheetvalue.024681004812162024Qg,GATECHARGE(nC)VGS,GATE-SOURCEVOLTAGE(V)ID=10AVDS=5V15V10VVSPQG(SW)VTH040080012001600051015202530VDS,DRAINTOSOURCEVOLTAGE(V)CAPACITANCE(pF)CISSCRSSCOSSf=1MHzVGS=0VUsethisforCISS70%75%80%85%90%95%100%051015202530EfficiencyOutputCurrentEfficiencyfor1.4VOutput@F=200KHzVin=10Vin=12Vin=140.00.51.01.52.02.53.03.54.0051015202530PowerLoss(W)OutputCurrentTotalLossesfor1.4VOutput@F=200KHzVin=14Vin=12Vin=10Part#High-SideVDRIVELow-SideVDRIVEHigh-SidePull-upResistanceHigh-SidePull-downResistanceLow-SidePull-upResistanceFAN5009121241.24FAN50684.851.81.81.8FAN50694.851.81.81.8FAN50784.851.81.81.8FAN52304.85746FAN52334.85746FAN52344.8583.28FAN52354.85746FAN52364.85122.412FAN52404.853.81.63.8FAN52504.853.81.63.8FAN6520A4.852.522.5Low-SidePull-downResistanceAdaptiveDead-timeThresholdDeadTimeL-HDeadTimeH-LControllerQuiescentPower(mW)ThetaJ-A1.214020601401.21251075381.212510161001.21251075385125207885125207881.5125204.251105125207881.21252010880.81382010880.81252058811251015140Unlessotherwisenotedincomment(hovermouseovercolumnheadingtoreadcomment),usetypicalparameterfromdatasheet.BluecolumnheadingshavefurtherexplanationintheDefinitionstab.Clickontheheadingtoreadexplanation.Greyfieldsarecalculatedfieldsforreferenceonly(notusedforlosscalculations)Part#RDS(ON)4.5RDS(ON)10DeltaRGVSPVTHCISS0CISSCRSSCOSSQGSFDB6670AL6.7534%1.32.51.54,0004,0002508209.0FDD629697.520%1.32.61.71,7001,4401404004.0FDD88809729%2.32.61.71,7001,2601502603.8FDD88965.74.721%2.12.61.73,2002,5253004906.9FDB66764.54.35%1.22.61.56,6346,63490083613.0FDB6676S65.59%1.22.61.56,0656,06585082610.0FDB66884.63.531%1.23.525,0005,0001,5001,40011.0FDB7030BL107.337%1.32.61.53,0003,0001885007.0FDC6401N554522%221.240040025821.0FDC645N25239%1.52.251.42,0001,460962273.6FDC6561AN1138238%231300300191000.7FDD370687.57%1.51.80.92,3001,8804302013.7FDD6512A1621.80.91,5001,500942772.0FDD6530A2621.80.91,0001,000631801.3FDD66447.56.515%1.32.51.53,5003,0871856007.5FDD6680A10825%1.52.51.63,0003,0001885007.0FDD66968.66.532%1.5322,2001,7151804105.0FDS6612A261937%1.22.81.61,2001,200751852.8FDS6678A201811%1.22.41.41,8001,8001132273.6FDS6690A131030%1.22.81.62,0002,0001253505.0FDS669211.11011%1.52.51.52,8002,1641383575.0FDS669411.19.122%1.25321,5001,500943424.0FDS6812A17166%1.21.80.81,7001,7001062772.0FDS6986SQ1342821%1.82.71.6900900