Patent ID: 8183835

Claim:
A battery pack, comprising: a protection circuit configured to detect over-charge, over-discharge and over-current of a rechargeable battery in order to turn off a switch element, the switch element being provided at a wire provided between the rechargeable battery and a load circuit or between the rechargeable battery and a charging device; a series circuit of a thermistor and a resistor, the series circuit being provided in parallel to the rechargeable battery, the thermistor being thermally connected to the rechargeable battery; and an abnormal temperature detection unit provided in the protection circuit, wherein the abnormal temperature detection unit operates the switch to be in an off state in a case where a temperature of the rechargeable battery detected by the thermistor is higher than a predetermined temperature, in a case where a voltage of the wire provided between the rechargeable battery and the load circuit or between the rechargeable battery and the charging device is higher than a threshold voltage of a forward drop voltage of a body diode in the switch, the abnormal temperature detection unit operates the switch to be in an on state, and the abnormal temperature detection unit includes: a first comparator configured to compare a voltage of a connection node between the thermistor and the resistor and a reference voltage corresponding to the predetermined temperature; a second comparator configured to compare the voltage of the connection node and the threshold voltage of the forward drop voltage of the body diode in the switch; and a flip flop, wherein when the temperature of the rechargeable battery exceeds the predetermined temperature, the flip flop is set by an output signal of the first comparator, and when the voltage of the wire exceeds the threshold voltage, the flip flop is reset by an output signal of the second comparator.