Patent attributes
A signal indicating temperature of an IGBT chip, after input into an overheat detection terminal, is simultaneously input into a first comparator for protection operation and a second comparator for precaution. At a normal time when the chip temperature is low, a first transistor connected to an alarm signal output terminal via a resistor and a second transistor connected to the alarm signal output terminal via a Zener diode are turned off, and the alarm signal output terminal whose voltage is pulled up by an external pull-up circuit is set to high level voltage. When the second comparator detects a precaution condition, the second transistor is turned on, and the alarm signal output terminal is set to intermediate level voltage. When the first comparator detects chip overheat, the first transistor is turned on, and the alarm signal output terminal is set to low level voltage.
