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Charge and discharge protection circuit and battery pack with high withstand voltage

  • US 5,936,384 A
  • Filed: 06/04/1998
  • Issued: 08/10/1999
  • Est. Priority Date: 06/09/1997
  • Status: Expired due to Term
First Claim
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1. A charge and discharge protection circuit coupled to one of a secondary battery and a charger, for protecting the secondary battery from an overcharge state, an overdischarge state and an over-current state, comprising:

  • an overcharge detecting circuit for monitoring how the secondary battery is charged and for generating an overcharge detection signal;

    a level shifting circuit for receiving the overcharge detection signal from the overcharge detecting circuit and for generating a charge control signal;

    an overdischarge detecting circuit for monitoring how the secondary battery discharges itself and for generating an overdischarge detection signal;

    an over-current detecting circuit for detecting an over-current state of the secondary battery and for generating an over-current detection signal;

    a delay circuit for setting a delay time used when one of an overdischarge state and an over-current state is detected;

    a short circuit detecting circuit for detecting a short circuit state and for generating a short circuit detection signal;

    a plurality of protection diodes for protection of the overcharge and overdischarge protection circuit from static electricity, and whereintransistors constituting the level shifting circuit that potentially receive a relatively high voltage from the charger as one of a source level and a drain level have a high withstand voltage construction.

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