PURPOSE: To allow constant detection of abnormality depending on the characteristics of load by comparing the power supply voltage to be fed to a load with a reference voltage thereby detecting overcurrent.

CONSTITUTION: Upon receiving an input signal from a microcomputer 5 rectified through a charge pump circuit 11, the reference generating circuit 2 in a power IC 1 generates a reference voltage having a waveform preset depending on the characteristics of a load 6 and delivers the reference voltage to a comparator circuit 4. A monitor circuit 3 monitors the drain/source voltage of an output MOS 12 and delivers the monitored voltage to the comparator circuit 4. A comparator 41 in the comparator circuit 4 compares a reference voltage from the reference generating circuit 2 with a monitor voltage from the monitor circuit 3 and delivers the comparison results to an AND circuit 10. This circuitry allows constant detection of abnormality depending on the characteristics of the load 6.