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Methods of and apparatus for controlling power drawn by an appliance through a USB port

  • US 8,689,022 B2
  • Filed: 08/30/2011
  • Issued: 04/01/2014
  • Est. Priority Date: 08/30/2011
  • Status: Active Grant
First Claim
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1. Apparatus for controlling power drawn by an appliance from a power source through a USB port having D+ and D−

  • data lines, a power line, and a ground line, the apparatus comprising;

    a pull-down resistor switchingly connectable to the D+ data line;

    a current source switchingly connectable to the D+ data line;

    a voltage source switchingly connectable to the D+ data line;

    a voltage sensor in communication with the data lines; and

    a controller programmed to selectively connect the pull-down resistor, the current source, and the voltage source to the D+ data line and to limit any electrical current drawn from the power source to any of a first level through a seventh level according to voltage levels on the D+ and D−

    data lines.

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