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Battery Charging Method and Circuit

  • US 20140184173A1
  • Filed: 12/29/2012
  • Published: 07/03/2014
  • Est. Priority Date: 12/30/2011
  • Status: Active Grant
First Claim
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1. A method to control a composite battery charger charging a battery having a battery voltage, comprised of a combination of a switching regulator and a linear battery charger, the switching regulator including a power switch which is turned on and off with a duty cycle by a pulse width modulator (PWM) and the switching regulator having an output voltage providing supply voltage for the linear battery charger and for one or more device circuits consuming a device current, the method comprising:

  • turning a pass transistor of the linear charger substantially fully on in a constant current (CC) operating mode;

    generating a control signal based on a difference of a signal representative of a sensed battery charge current provided through the pass transistor and a first reference value based on a target battery charge current; and

    controlling the duty cycle of the power switch based on the control signal to maintain a battery charge current substantially constant approximately corresponding to the first reference value, substantially independently of the battery voltage and the device current.

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