Semiconductor device for conducting primary current upon receipt of a control signal

摘要

A semiconductor device comprising first and second transistors connected in series with one another to provide a path for a primary current upon receipt of a control signal at the gate of the second transistor. The first transistor is coupled to receive a base current from a secondary power source. A third transistor is coupled to have a current path which shunts the base current of the first transistor upon conduction of the third transistor. A zener diode is connected between the base of the third transistor and the common junction of the first and second transistors and is arranged to provide base current to the third transistor thereby causing the third transistor to be conductive upon turn-OFF of the second transistor, and as a consequence quickly turning OFF the first transistor. The base current provided through the zener diode to the third transistor is enhances by spike voltages generated by floating inductance in wiring connecting the first transistor to the second transistor, which enhances conduction of the third transistor upon turn-OFF of the second transistor to facilitate turn-OFF of the first transistor.