Patent ID: 7550950

Claim:
A battery pack protection circuit comprising: at least one switching element which has a control terminal, for being connected in series to a positive pole or a negative pole of a battery cell, for being turned off during an abnormality for shutting off a current path for charging/discharging the battery cell; and a protective control circuit connected to the control terminal of the at least one switching element such that the at least one switching element can be turned off when an abnormal current flows through the current path, the protective control circuit further having a signal input terminal for receiving a signal showing an abnormal state other than the abnormal current, the at least one switching element being turned off when a signal showing said abnormal state is input to the signal input terminal, wherein a first positive temperature coefficient thermistor thermally connected to the at least one switching element is further provided, and a signal corresponding to a change in the resistance of the first positive temperature coefficient thermistor due to overheating of the switching element to which the first positive temperature coefficient thermistor is thermally connected is input, as the signal showing the abnormal state, to the signal input terminal.