SEMICONDUCTOR PROTECTING DEVICE

摘要

PROBLEM TO BE SOLVED: To obtain a semiconductor protecting device which uses poly- crystalline silicon as an active region so as to suppress a current flowing into a main semiconductor switch below a set value. SOLUTION: An IGBT 11, which uses a signal-crystal silicon substrate as an active region has a gate electrode connected to a control signal source PG via a gate driver 13. The IGBT 11 has a sense terminal 11s for making a branched sense current flow. To a node between the gate driver 13 and the gate electrode of the IGBT 11, a shunting N-MOSFET 15 is connected in order to protect the IGBT 11 against an overcurrent. The gate of the MOSFET 15 is connected to the sense terminal 11s via a voltage detector 21 arranged in a sense circuit 20. The MOSFET 15 and voltage detector 21 use a polycrystalline silicon semiconductor layer as an active region.