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Battery charging apparatus and method with charging mode convertible function

  • US 5,994,875 A
  • Filed: 06/24/1997
  • Issued: 11/30/1999
  • Est. Priority Date: 06/24/1996
  • Status: Expired due to Term
First Claim
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1. A battery charging apparatus for charging at least one battery in at least one of a constant current mode and a constant voltage mode, comprising:

  • a switching regulator for generating a switching voltage from a DC voltage source;

    a constant current charging control means for detecting a current of a DC output provided by the switching regulator to produce a charging control signal for enabling the switching regulator to operate in the constant current mode;

    a battery detection means for detecting a voltage level of the at least one battery;

    a control means for producing a charging mode selection signal CHG-- MOD, a charging speed control signal F--, and a charging enable signal CHG-- EN in response to the voltage level detected from the battery detection means, the charging enable signal CHG-- EN for permitting the switching regulator to start charging for the at least one battery, said control means for producing the charging mode selection signal CHG-- MOD to convert from charging in the constant current mode to charging in the constant voltage mode without interruption of charging in the constant current mode to determine if at least one of a preset voltage level and a preset charging condition has been reached;

    a charging speed control means for enabling the switching regulator to perform a fast charging operation in response to an input level of the charging speed control signal F-- Q;

    a constant voltage charging control means for outputting a control signal to a feedback input terminal of the switching regulator in response to the charging mode selection signal CHG-- MOD to operate the switching regulator in the constant voltage mode if at least one of the voltage level of the at least one battery has reached the preset voltage level an the preset charging condition has been reached;

    a protection means for preventing the constant voltage charging control means from being damaged by an excessive surge voltage; and

    a charging mode selection means for enabling the constant voltage charging control in response to the charging mode selection signal CHG-- MOD.

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