INSULATED GATE TYPE SEMICONDUCTOR DEVICE WITH OVER CURRENT DETECTING FUNCTION

摘要

PROBLEM TO BE SOLVED: To attain a semiconductor device which can improve overcurrent detecting precision, regardless of the fluctuations in a main current. SOLUTION: This semiconductor device is provided with a sense resistor 4, which converts emitter sense current Is outputted from an IGBT 3 having an emitter sense current terminal Ts into a sense voltage Vo, a comparator 6A outputting a signal L as the over current detection signal Vcom of the IGBT 3 by comparing the sense voltage Vo with a reference voltage Vref, and an operational amplifier 7 virtually-shorting the circuit between an emitter sense main terminal Tm and the emitter sense current terminal Ts. The voltage of the emitter sense current terminal Ts and that of an emitter main terminal Tm become roughly equal, regardless of the magnitude of a main current Ic. It is thus possible to always keep the ratio of the main current Ic to the sense current Is roughly constant, thereby precisely detecting the overcurrent.