Patent ID: 7248452
Filing Date: 2007-07-24
Classification: H02H,H03K

Abstract:
1. A method of protecting a semiconductor device, comprising the steps of: providing a DC power source, a load, and a semiconductor device arranged between the DC power source and the load; providing a circuit element connected to the semiconductor device; switching the semiconductor device so that the load is changed between a driving state and a stopping state; cutting off a conduction of the semiconductor device between the DC power source and the load when a voltage drop across the semiconductor device exceeds a predetermined reference voltage; and setting a constant of the circuit element so that the reference voltage is not greater than a critical voltage, wherein the critical voltage is a product of an on-resistance of the semiconductor device when its channel temperature is at an upper limit of a permissible temperature, and a minimum current value which causes the channel temperature to reach the upper limit of the permissible temperature by the self-heating due to Joule heat.