A semiconductor device which IGBT (Z1) and a control circuit (B1)
for driving the IGBT (Z1) are formed on the same semiconductor substrate
by using a junction isolation technology, includes an input terminal (P1)
for inputting a drive signal of the IGBT (Z1), a Schottky barrier diode
(D2) having an anode connected to the input terminal (P1) and a cathode
connected to an input terminal (B11) of the control circuit (B1),
and a p-channel MOSFET (T1) for shorting both ends of the Schottky barrier
diode (D2) when the voltage of the drive signal input to the input terminal
(P1) is higher than a predetermined voltage, thereby latch-up of the parasitic
element is prevented and a transmission loss of the input signal can be reduced.
