Patent ID: 7948277

Claim:
A drive circuit for a semiconductor element, comprising: a control circuit which turns “ON” and “OFF” the semiconductor element in correspondence with “ON” and “OFF” signals from outside, respectively; a sampling circuit configured to receive an input of the “ON” signal from the control circuit and an input of a signal directly from a gate of the semiconductor element, and configured to determine a time period in which a detection process is permitted for a controlled variable of the semiconductor element, the time period being determined based on the input of the “ON” signal and the input of the signal directly from a gate of the semiconductor element, wherein the determined time period is a period that corresponds to a controlled variable Qon of the semiconductor element at a time point when said control circuit has inputted the “ON” signal; and a controlled-variable detection circuit which receives an input of the determined time period from the sampling circuit and compares a controlled variable Qt of the semiconductor element as is detected within the determined time period, and a controlled-variable comparison value Qs that is set beforehand, thereby to output an abnormality occurrence signal for the semiconductor element.