Abstract: A charge pump circuit receives a battery voltage of a power line, and outputs a raising voltage proportional to the battery voltage. A low voltage detecting circuit detects a low voltage state in which a detecting voltage obtained by dividing the raising voltage. Thus, it is possible to indirectly detect a low voltage state in which the battery voltage is lower than a predetermined threshold value. When the low voltage state is detected, a drive circuit turns off a MOSFET. At this time, the battery voltage is temporarily varied, but the charge pump circuit has a filter action and a delay action, whereby temporary variation does not easily appear in the raising voltage (detecting voltage), and an error in operation of the MOSFET can be prevented.

Abstract: In a load drive circuit, a charge pump circuit inputs a battery voltage of a power line, and outputs a raising voltage proportional to the battery voltage. A low voltage detecting circuit detects a low voltage state in which a detecting voltage obtained by dividing the raising voltage is lower than a reference voltage. Thus, it is possible to indirectly detect a low voltage state in which the battery voltage is lower than a predetermined threshold value. When the low voltage state is detected, a drive circuit turns off a MOSFET. At this time, the battery voltage is temporarily varied, but the charge pump circuit has a filter action and a delay action, whereby temporary variation does not easily appear in the raising voltage (detecting voltage), and an error in operation of the MOSFET can be prevented.