Semiconductor drive device and power conversion apparatus

Abstract

First and second current detection resistors connected in series are used as current detection resistors for detecting a main current of a switching element. A single-fault detection circuit divides a voltage detected from the main current by first to third resistors. A first comparator compares a voltage at a Detect terminal with a voltage at a connection point of the first and second resistors, and a second comparator compares the voltage at the Detect terminal with a voltage at a connection point of the second and third resistors. When either one of the first and second current detection resistors is short-circuited, the corresponding one of the first and second comparators outputs an L-level signal. Accordingly, an AND circuit outputs a signal indicating a single fault. Since this signal reduces a threshold voltage of the individual comparator by half, the same output voltage as before the fault is maintained.