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Charging system for battery powered devices

  • US 5,523,671 A
  • Filed: 07/23/1993
  • Issued: 06/04/1996
  • Est. Priority Date: 02/14/1991
  • Status: Expired due to Term
First Claim
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1. Apparatus for controlled battery charging in which a battery is connectable to a power source capable of providing charging current at a suitable terminal voltage, the apparatus comprising:

  • a switch circuit for regulating the charging current of said battery responsive to a variable control signal, said switch circuit connected in series between said battery and said power source;

    a circuit connected to said switch circuit for determining said battery charging current and generating a signal proportional thereto;

    a control circuit connected to said switch circuit and to said current determining circuit for applying said control signal to said switch circuit, said control circuit comprising logic for;

    i). varying said control signal responsive to said current proportional signal, to cause said switch circuit to progressively increase said charging current until said charging current reaches a defined maximum value,ii). maintaining said control signal until said charging current reaches a defined minimum value, andiii). varying said control signal to cause said switch circuit to progressively increase said charging current until said charging current reaches said defined maximum value, thereby maintaining said charging current between said maximum value and said minimum value; and

    termination logic for terminating said battery charging when said current begins to increase while said control logic is maintaining said selected control signal, as an indication that said battery has reached a fully charged condition.

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