Patent ID: 6992463

Claim:
A battery protection circuit used to control the operation of a first switch circuit and a second switch circuit inserted in series in a power supply path between battery cells and an external power source, comprising a first protecting controller, having an interface circuit for receiving a command signal output from a controller monitoring whether the voltage of the battery cells is higher than a first voltage, and generating a control signal for controlling operation of the first switch circuit, a second protecting controller, having an over-voltage detector that detects whether the voltage of the battery cells is higher than a second voltage or higher than the first voltage, and generating a control signal for controlling the operation of the first switch circuit and a second control signal for controlling the turning off of the second switch circuit; wherein, when the over-voltage detector of the second protecting controller detects that the voltage of the battery cells is higher than said second voltage, a control signal for turning off the first switch circuit is generated; then, when the voltage of the battery cells remains higher than the second voltage after a prescribed time, the second control signal is generated for turning off the second switch circuit.