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Control loop for pulse charging lithium ion cells

  • US 5,898,294 A
  • Filed: 08/19/1997
  • Issued: 04/27/1999
  • Est. Priority Date: 08/19/1997
  • Status: Expired due to Fees
First Claim
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1. Control circuitry for regulating charging current from a current source to a battery, the battery comprising a positive terminal having a positive terminal voltage associated therewith, a negative terminal, and a battery voltage between the positive and negative terminals, the control circuitry comprising:

  • a switch for transmitting the charging current from the current source to the positive terminal of the battery, the switch having a gate terminal;

    a charge pump for driving the gate terminal of the switch above the positive terminal voltage;

    a comparator stage with hysteresis for gating the charge pump; and

    a filtering stage for sensing the battery voltage and driving the comparator stage;

    wherein the control circuitry regulates an average value of the battery voltage by pulse width modulating the charging current.

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