Patent ID: 7196523

Claim:
A circuit for monitoring charge/discharge of a battery, comprising: a first terminal connected to one end of a single current detection resistor serially connected to the battery so as to detect a charge current or a discharge current of the battery; a second terminal connected to the other end of the current detection resistor; a converter that converts a terminal potential of the first terminal at which a potential of the one end of the current detection resistor appears and a terminal potential of the second terminal at which a potential of the other end of the current detection resistor appears, into currents respectively; a first terminal capacitor that develops an integrated voltage with supply of the current as converted by the converter from the terminal potential of the first terminal; a second terminal capacitor that develops an integrated voltage with supply of the current as converted by the converter from the terminal potential of the second terminal; a comparator that compares the integrated voltages developed by the first and second terminal capacitors with a reference voltage; and an output section that outputs a difference between the number of times of change in an output of the comparator, the output changing when the integrated voltage of the first terminal capacitor reaches the reference voltage, and the number of times of change in an output of the comparator, the output changing when the integrated voltage of the second terminal capacitor reaches the reference voltage.