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Improvements in battery charging circuits

  • US 5,307,002 A
  • Filed: 06/05/1991
  • Issued: 04/26/1994
  • Est. Priority Date: 06/06/1990
  • Status: Expired due to Fees
First Claim
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1. An AC adaptor, separate from and adapted to be connected to portable electronic equipment, for supplying a DC output to power the equipment and for charging a battery used to provide the backup power to the equipment when an AC mains supply is not available to power the AC adaptor, the adaptor comprising:

  • supply means for converting the AC mains supply to a DC supply;

    current control means connected to said supply means for sensing and controlling the current supplied to the battery and to the equipment;

    battery voltage monitoring means for measuring the potential of the battery;

    means responsive to said monitoring means for determining a maximum said potential to indicate a fully charged state of the battery, the current control means being responsive to said determining means to reduce the current supplied to the battery when the fully charged state is determined;

    means for sensing connection of the adaptor to the AC mains supply and for electrically disconnecting the battery from the equipment in response thereto; and

    means for connecting the adaptor to the equipment;

    wherein said battery voltage monitoring means comprises switch means connected in series with the battery and switch control means for repeatedly opening said switch means to interrupt the charging current to the battery, the monitoring means measuring said potential when said switch means is open.

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