FuseSelectionGuide保险丝选择指南.pdf

《FuseSelectionGuide保险丝选择指南.pdf》由会员上传分享，免费在线阅读，更多相关内容在行业资料-天天文库。

1、TECHNICALPAPERFuseSelectionGuide:RaychemSurfaceMountChipFusesSelectingRaychemSurfaceMountChipFusesSteadyStateDeratingFuseselectionseemsstraightforwardinthatyoupickoneItisrecommendedthatRaychemsurfacemountchipfusesnotwhichhasacurrentratingjustabithighert

2、hanyourworst-beoperatedatsteadystatecurrentsgreaterthan75%ofthecasesystemoperatingcurrent.Unfortunately,it’snotthatsim-nominal25°Ccurrentrating.ple.TherearederatingconsiderationsforoperatingcurrentandApplyStandardDerating(75%)applicationtemperature.Turn

3、-onandothersystemoperations(likeprocessorspeedchangesormotorstartup)causecurrentIfuse≥Isys/0.75surgesorspikesthatalsorequireconsiderationwhenselectingWhere:afuse.SoselectingtherightfuseforyourapplicationisnotasIfuseistherateddatasheetcurrentat25°Csimple

4、asknowingthenominalcurrentdrawnbythesystem.IsysisthenominalsteadystatesystemcurrentHowever,byfollowingtheguidelinepresentedinthispaper,selectingtheproperfusedoesbecomeastraightforwardTemperatureDeratingprocess.Afuseisatemperaturesensitivedevice.Therefor

5、e,operatingtemperaturewillhaveaneffectonfuseperformanceandlife-FuseSelectionFlowcharttime.OperatingtemperatureshouldbetakenintoconsiderationThebasicconsiderationsforfuseselectionareshownintheflow-whenselectingthefusecurrentrating.TheThermalDeratingchart

6、presentedinFigure1.FollowingthisflowchartwillhelpyouCurveforRaychemsurfacemountchipfusesispresentedinselectafusebestsuitedforyourapplicationconditions.Figure2.Useittodeterminethederatingpercentagebasedonoperatingtemperatureandapplyittothederatedsystemcu

7、rrent.Step1—Step2—DetermineDetermineSteadyPulseWaveformbyApplyTemperatureDeratingStateFuseCurrentCalculatingI2tTheminimumfusecurrentratingisdeterminedbythefollow-Ratingingformula:ApplyStandardIfuse≥(Isys/0.75)/KtempSteadyStateStep3—ApplyPulseDerating(75

8、%)Where:CycleDerating[Ifuse≥Isys/0.75]Ktempisthe%deratingdeterminedfromtheThermalDeratingCurveinFigure2Step4—ApplyPulseThermalDeratingCurve110TemperatureDeratingApply10090Temperature80Derating7088%[Ifuse≥Isys/0.75/Ktemp]Step5—App