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USB power supply apparatus

  • US 9,804,619 B2
  • Filed: 10/21/2015
  • Issued: 10/31/2017
  • Est. Priority Date: 10/24/2014
  • Status: Active Grant
First Claim
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1. A USB power supply apparatus that conforms to the USB (Universal Serial Bus) specification, and that supplies electric power to a USB power reception apparatus, the USB power supply apparatus comprising:

  • a power supply circuit;

    a bus line structured to connect an output of the power supply circuit and the USB power reception apparatus;

    a switch provided on a path of the bus line;

    a feedback circuit structured to feedback control the power supply circuit such that the output voltage of the power supply circuit approaches a reference voltage; and

    a controller structured to adaptively control the reference voltage based on an electrical state of the USB power supply apparatus;

    wherein the controller controls the reference voltage so as to reduce an amount of a drop in voltage from a predetermined setting voltage that occurs in a bus voltage at a position that is closer to the USB power reception apparatus side than the switch;

    wherein the controller comprises a bus voltage detection unit structured to detect the bus voltage,wherein the controller controls the reference voltage based on a detection result obtained by the bus voltage detection unit;

    wherein the bus voltage detection unit compares the bus voltage with a first threshold voltage determined to be lower than the setting voltage, and generates a low voltage detection signal which is asserted when the bus voltage becomes lower than the first threshold voltage;

    wherein, when the low voltage detection signal is asserted, the controller raises the reference voltage by a predetermined voltage increment;

    wherein the bus voltage detection unit compares the bus voltage with a second threshold voltage that is set to the setting voltage or otherwise a value in the vicinity of the setting voltage;

    wherein the bus voltage detection unit generates a voltage return signal that is asserted when the bus voltage exceeds the second threshold voltage;

    and wherein, when the voltage return signal is asserted, the controller lowers the reference voltage by a predetermined voltage decrement.

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