Characteristics
1.On-statecharacteristics:modulationeffectoccursinthebaseareaandcollectorareaunderlargeinjection,andtheon-statevoltagedropisverylow.
2.Switchingcharacteristics:Currentconcentrationintheturn-offprocess:Duetotheself-biaseffectinthebaseregion,theedgeoftheemitterisreverselybiasedduringtheturn-offprocessofthetransistor,theedgeisturnedoffbutthecenterisstillturnedon,socurrentconcentrationoccurs
3.Thesecondarybreakdowncharacteristicsarethesameasallrelays.Itisworthnotingthatafterthefirstavalanchebreakdown,theabilityaddedtotheBJTexceedsthecriticalvaluebeforethesecondarybreakdownoccurs,whichmeansthatthesecondarybreakdownrequiresenergy.
Mainapplication
1.Asanamplifier,usedinpowersupplyseriesvoltageregulatorcircuit,audioandultrasonicamplificationandotherfields
2,asahigh-powersemiconductorswitch,TVlineoutputcircuit,motorcontrol,uninterruptedpowersupplyandautomotiveelectronics
3,GTRmodule,usedinACdrives,invertersandswitchingpowersupplies.
Workingmode
1.WhentheBEjunctionisforwardbiasedandtheCBjunctionisreversebiased,thepowertransistorisinamplifyingmode
2.WhentheBEandCBjunctionarebothWhenforwardbiased,thepowertransistorisinsaturationmode
3.WhentheBEjunctioniszerobiasedorreversebiased,andtheCBjunctionisreversebiased,thepowertransistorisincut-offmode.
Theamplificationeffectofthepowertransistorisasfollows:asmallerbasecurrentcancontrolalargercollectorcurrent;orasmallerpowercanbescaleduptoalargerpower.
Mainparameters
1,ratedvoltage
2,currentrating:collectormaximumcurrentIcm,collectorcontinuouscurrentIc
3.Themaximumpowerdissipationofthecollector:Pcm(whenthecaseis25℃)
4,themaximumjunctiontemperatureTmj(usually150℃)
5,theswitchingtime:ONTime,storagetime,falltime