Abstract: A detection circuit detects an abnormal current which flows through a first output transistor. In this event, the first output transistor is connected to an external power supply via a load resistor. The above detection circuit mainly includes a second transistor, a constant current supply, a third transistor, a fourth transistor, and a comparator circuit. The constant current supply supplies a constant current into the second transistor. Further, the third transistor is connected to the first output transistor and performs an ON-OFF operation in synchronism with the first output transistor. On the other hand, the fourth transistor is connected to the third transistor in serial and performs the ON-OFF operation opposite to the first output transistor. Moreover, the comparator circuit has a first input and a second input.