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Method and apparatus for charging batteries having different voltage ranges with a single conversion charger

  • US 9,209,676 B2
  • Filed: 12/07/2012
  • Issued: 12/08/2015
  • Est. Priority Date: 12/07/2012
  • Status: Active Grant
First Claim
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1. A battery charger, comprising:

  • a single conversion switched mode power supply including a power transformer, the transformer defines a primary side and a secondary side of the battery charger and converts an input alternating current (AC) power on the primary side to a direct current (DC) charging current on the secondary side, the DC charging current is provided to charging interface configured to connect to a rechargeable battery;

    a bias winding on the primary side of the power transformer that provides an output corresponding to output of the secondary side of the power transformer;

    a programmable voltage sensing circuit that senses the output of the bias winding and produces a voltage sensing output that is proportional to the output of the bias winding by a selected factor;

    a comparison circuit that compares the voltage sensing output to a reference voltage and generates a fault signal when the voltage sensing output exceeds the reference voltage; and

    the single conversion switched mode power supply include a switched mode control circuit that controls the single conversion switched mode power supply to produce the DC charging current, and which shuts off the switched mode power supply responsive to the fault signal; and

    a programmable current sensing circuit on the primary side that produces a current sensing signal that is selectively proportional to the charging current, and the current sensing signal being provided to the comparison circuit, and the comparison circuit produces the fault signal if the current sensing signal indicates the DC charging current has exceeded an over-current limit.

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