Patent ID: 6198252
Filing Date: 2001-03-06
Classification: G01R,H01M,Y02E

Abstract:
A battery state monitoring circuit for controlling the charge/discharge state of a secondary battery by controlling the on/off state of a switch element, and for monitoring a voltage and a discharge current of the secondary battery, comprising:at least one switch element for controlling the charging and discharging of the secondary battery;a sense resistor connected to a terminal of the secondary battery;an amplifier for amplifying a voltage across the sense resistor;a microcomputer for controlling the on/off state of the at least one switch element in accordance with a voltage or a current of the secondary battery, calculating a charge or discharge current of the secondary battery by monitoring the voltage across the sense resistor, and shutting off the amplifier when monitoring the voltage of the secondary battery;a voltage regulator for regulating a voltage of the secondary battery and supplying a regulated voltage to the microcomputer;a voltage detecting circuit for detecting the regulated voltage output by the voltage regulator and outputting a signal indicating if the regulated voltage falls below a predetermined voltage level for suspending a calculating function of the microcomputer; anda control circuit for maintaining the amplifier in a non-operational state by outputting a ground level voltage to the amplifier when the voltage detecting circuit detects a voltage lower than the predetermined voltage level.