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Battery charging with dynamic current limiting

  • US 9,948,124 B2
  • Filed: 08/28/2012
  • Issued: 04/17/2018
  • Est. Priority Date: 09/13/2011
  • Status: Active Grant
First Claim
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1. A system configured to charge a battery of a device while the device is operating, the system comprising:

  • an input connector configured to electrically couple the system with an external supply source to receive a supply voltage and a supply current, wherein the external supply source has a maximum supply current, and wherein the external supply source is a separate and discrete device from the system;

    a device connector configured to electrically couple the system with the device to receive a device current, wherein the device draws power received through the device connector from the external supply source, wherein the device current has an amount that varies over time with operating conditions of the device;

    a first sink circuit configured to draw a sink current from the supply current received through the input connector, wherein first sink circuit is configured such that an amount of the sink current indicates an amount of the supply current of the external supply source received through the input connector;

    a second sink circuit configured to draw a bias current from the supply current received through the input connector, wherein the second sink circuit is configured such that an amount of the bias current indicates an amount of the maximum supply current of the external supply source;

    a sampling circuit that is electrically coupled with the first sink circuit and the second sink circuit, such that a voltage drop across the sampling circuit is based on the sink current and the bias current; and

    a charge control circuit configured to sample the voltage drop across the sampling circuit and to control a charge current to charge a battery from the supply current based on the sampled voltage drop, the charge current being received through the input connector, wherein the charge control circuit is configured such that an amount of the charge current combined with the varying amount of the device current of the device is maintained below the maximum supply current;

    wherein the system is configured to simultaneously power the battery and the device.

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