Patent ID: 7443645

Claim:
An overcurrent detecting device for detecting an overcurrent in a load circuit for controlling ON/OFF of a load by using a semiconductor switch, comprising: a driver circuit that outputs a driving signal to the semiconductor switch; a reference voltage generating circuit that generates a reference voltage; a measured voltage generating circuit that generates a measured voltage corresponding to a voltage generated across the semiconductor switch; a first comparator that compares the measured voltage with the reference voltage and outputs an overcurrent determination signal when the measured voltage is greater than the reference voltage; a saturation determining circuit that determines that a differential voltage between a control voltage of the semiconductor switch and a voltage to be applied to a positive side of the semiconductor switch is greater than a predetermined voltage; and an overcurrent signal switching circuit that performs a switching operation so as to enable the overcurrent determination signal to be output to the driver circuit when the saturation determining circuit determines that the differential voltage is greater than the predetermined voltage.