USB power supply apparatus
AssigneeRohm Co., Ltd.
InventorKenichi Motoki
Life of this patent
Estimating the term…
Abstract
A USB power supply apparatus supplies electric power to a USB power reception apparatus. A bus line connects the output of the power supply circuit and the USB power reception apparatus. A switch is provided on a path of the bus line. A feedback circuit feedback controls the power supply circuit such that the output voltage VOUT of the power supply circuit approaches a reference voltage VREF. A controller adaptively controls the reference voltage VREF based on an electrical state of the USB power supply apparatus.
Claims13
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.
Dependencies are inferred from the claim text.