Patent ID: 7391185

Claim:
A battery pack protection circuit comprising: a first switching element which shuts off a discharging current flowing from a battery cell; a second switching element which shuts off a charging current flowing to the battery cell; and a protective control circuit which detects an abnormal state of the voltage, current, or ambient temperature of the battery cell and which controls the first and second switching elements to protect the battery cell from the abnormal state, further comprising a switching element control circuit including a plurality of positive temperature coefficient thermistors connected in series, the plurality of positive temperature coefficient thermistors being thermally connected to at least two of the first switching element, the second switching element, and the battery cell and being inserted into a control signal path of at least one of the first and second switching elements, so as to shut off the corresponding first or second switching element, on the basis of an increase in the resistance of the positive temperature coefficient thermistor during overheating of the first switching element, the second switching element, or the battery cell.