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Charge-pump biased battery protection circuit

  • US 7,626,360 B2
  • Filed: 12/12/2006
  • Issued: 12/01/2009
  • Est. Priority Date: 08/11/2006
  • Status: Active Grant
First Claim
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1. A battery protection circuit for charging a battery from a charger and discharging said battery to a load, said circuit comprising:

  • a pair of battery terminals for connecting said battery;

    an input-output terminal for connecting at least one of said load and said charger;

    a pass transistor having a first drain/source connection coupled to a given one of said battery terminals and a second drain/source connection coupled to said input-output terminal;

    a charge-pump circuit having an output coupled to a gate of said pass transistor, wherein said charge pump circuit charges said gate of said pass transistor to a gate voltage such that a magnitude of a voltage between said gate of said pass transistor and said first drain/source connection is greater than a magnitude of a voltage across said battery terminals; and

    a second charge pump having an output coupled to a body of said pass transistor, for charging said body of said pass transistor to a voltage having a polarity opposite a polarity of said gate voltage with respect to both of said drain/source terminals of said pass transistor.

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