Patent ID: 6316915
Filing Date: 2001-11-13
Classification: H02J

Abstract:
A charge/discharge protection circuit for protecting a rechargeable battery of a battery pack from damage, comprising:a first terminal to which a negative electrode of a charger is connected;an internal detector unit having an input connected to the first terminal;an improper charger detector unit outputting a detection signal when an improper charger is connected to the battery pack and supplies a voltage exceeding a required charging voltage to the first terminal; andconnection cutoff means for cutting off, when the detection signal is output by the improper charger detector unit, the connection between the internal detector unit input and the first terminal, so that, when the improper charger is connected to the battery pack, a voltage of the input of the internal detector unit is avoided from being lower than a voltage of a second terminal to which a negative electrode of the battery is connected to substantially prevent variation of a threshold voltage of an input transistor in the internal detector unit when the improper charger is connected to the battery pack over an extended period of time.