Power supply apparatus for detecting battery voltage and the portions of faults

Abstract

A power supply apparatus according to the present invention includes a battery and a voltage detection circuit for detecting the voltage of the battery. The voltage detection circuit includes a differential amplifier which has a first input terminal for receiving a voltage based on the voltage of the battery and a second input terminal for receiving a predetermined triangular wave and outputs a rectangular wave with a pulse width modulated according to the voltage based on the voltage of the battery and a predetermined offset voltage, and an offset circuit which supplies the offset voltage to one of the first input terminal and the second input terminal so that the differential amplifier outputs a particular rectangular wave according to the offset voltage even when the voltage based on the voltage of the battery which is supplied to the first input terminal is 0.

Dependencies are inferred from the claim text.