mosfet 热阻测试

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1、MeasurementofMOSFETdevicesbyboosterdeviceMOSFETdevicescanbemeasuredusingthreedifferentelectricalsetups.1.ReversediodemeasurementInthefirstsetupweusethereversediodeofthedeviceforheatingandmeasurementalso.ThepowerstepisappliedusingthesocalledcurrentstepmethodbyswitchingfromahigherIforce+Isens

2、ecurrentleveltoIsensemeasurementcurrentandusingtheforwardvoltageastemperaturesensitiveparameter.toT3SterchannelIsenseIforceBothIforceandIsensecanbeprogrammedintheboosterwhichisaunipolardeviceofpositivepolarity.Thedevicevoltageistypicallybelow1V.2.MOSdiodemeasurementInthesecondsetupweconnect

3、theGatetotheDrainpinandmeasurethisthreeterminaldeviceasasocalledMOSdiode.WeapplyasimilarcurrentstepasdescribedaboveandmeasuretheforwardvoltageoftheMOSdiode.toT3SterchannelIsenseIforceThedevicevoltageistypically2..5Vcorrespondingtogatethresholdvoltage.Tony.he158-2079-5808Measurementwithheati

4、ngonchannelresistanceandsensingonreversediodeInthisthirdsetuptheelectricalconnectionisabitmorecomplex.toT3SterchannelIsenseIforceUGIntheheatingphasetheUGvoltageisathighlevelensuringcontinuousheatingcurrentthroughthechannelresistanceRDSon.Thepositiveheatingcurrentcomesfromtheboosterandanegat

5、ivesensecurrentisgeneratedbyanotherequipment,e.g.T3Ster.AtthestartofthecoolingIforceisswitchedoffandUGalsogoestozerothusclosingthetransistor.ThecontinuouslyflowingnegativeIsensecausesthereversediodetoopen.Thedevicevoltageistypicallylowonthechannelresistanceand-0.5Vonthereversediodeatcooling

6、.Apracticalproblemisthattheboosteroutputisofdevicesoflargesurfaceinordertoswitchhundredamperes.Thiscancauseleakageatnegativevoltages,resultinginlossofthemeasurementcurrentfromexternalsourceandnoiseinthemeasurement.Asimple“tandem”circuitrycanstopthisleakagewhilewithstandingthecurrentlevelsof

7、themeasurement.Tony.he158-2079-5808toT3SterchannelIsenseIforceUGT1T2DUTT1andT2aretransistorsofthesametypeandcharacteristics.T1isthedeviceundertest.T2behavesasacontrolswitchwhichisONduringheatingbutOFFduringcoolingsuchisolatingT1duringthecoolingmeasuremen