JFET, SenseFET, TempFET basics

[Stona]

senseFET
A power MOSFET with a split drain. Geometry determines a fixed ratio of the drain currents, about 1000 to one. The narrow, low-current drain contact is sensed to determine current in the high-current arm (the alternative is to place a small resistance in series with a single high-current drain, dissipating plenty of power and not getting high accuracy). Made by Motorola, Powerex and others.