Patent ID: 9356595
Filing Date: 2016-05-31
CPC Classification: H01L,H02M,H03K

Claim Text:
1. A method for switching current through a power semiconductor device which includes both an n-type emitter/collector region, and also a p-type base contact region, on each of both first and second surfaces of a p-type semiconductor die, and which has an ON state and an OFF state, comprising: at turn-on, when an external voltage difference is applied between the emitter/collector regions, shorting the more positive one of the emitter/collector regions together with the base contact region on the same one of the surfaces, to thereby conduct current through the power semiconductor device with a diode voltage drop characteristic of a p-n junction between the emitter/collector region on the other surface and the semiconductor die; and thereafter in the ON state, removing the shorting and flowing base current through the base contact region on the first surface, which is nearer the more positive one of the emitter/collector regions, without flowing base current through the base contact region on the second surface; during transition to the OFF state, in the OFF state, automatically enabling both a first voltage-limiting circuit which limits forward bias across a junction between the base contact region on the first surface and the emitter/collector region on the first surface to less than the forward diode voltage drop characteristic of the junction therebetween, and also a second voltage-limiting circuit which limits forward bias across a junction between the base contact region on the second surface and the emitter/collector region on the second surface to less than the forward diode voltage drop characteristic of the junction therebetween regardless of the voltage between the emitter/collector regions on the first and second surfaces; wherein the base contact region on the first surface is not electrically connected to the base contact region on the second surface, except through the semiconductor die itself; and wherein the emitter/collector region on the first surface is not directly electrically connected to the emitter/collector region on the second surface, except through the semiconductor die itself; whereby bidirectional switching is achieved with an on-state voltage drop which is less than a diode drop between the semiconductor die and a respective one of the emitter/collector regions.