USB POWER SUPPLY APPARATUS

• US 20160116928A1
• Filed: 10/21/2015
• Published: 04/28/2016
• Est. Priority Date: 10/24/2014
• Status: Active Grant

• Current Assignee: ROHM Co., Ltd.
• Original Assignee: ROHM Co., Ltd.
• Inventors: MOTOKI, Kenichi
• Granted Patent: US 9,804,619 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G05F 1/575 characterised by the feedback circuit

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 V_OUT of the power supply circuit approaches a reference voltage V_REF. A controller adaptively controls the reference voltage V_REF based on an electrical state of the USB power supply apparatus.

Claims

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 that connects 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 that feedback controls the power supply circuit such that the output voltage of the power supply circuit approaches a reference voltage; and

a controller that adaptively controls the reference voltage based on an electrical state of the USB power supply apparatus.

2. The USB power supply apparatus according to claim 1, 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.

3. The USB power supply apparatus according to claim 2, wherein the controller comprises a bus voltage detection unit that detects the bus voltage,

and wherein the controller controls the reference voltage based on a detection result obtained by the bus voltage detection unit.

4. The USB power supply apparatus according to claim 3, 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,

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

5. The USB power supply apparatus according to claim 4, wherein the reference voltage is configured as a voltage obtained by superimposing a correction voltage on the setting voltage,

and wherein, when the low voltage detection signal is asserted, the controller raises the correction voltage by a predetermined voltage increment.

6. The USB power supply apparatus according to claim 4, 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.

7. The USB power supply apparatus according to claim 6, wherein the reference voltage is configured as a voltage obtained by superimposing a correction voltage on the setting voltage,

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

8. The USB power supply apparatus according to claim 6, wherein, when the voltage return signal remains in an asserted state for a predetermined judgment time, the controller lowers the reference voltage.

9. The USB power supply apparatus according to claim 3, wherein the controller further comprises a current detection unit that detects a supply current which is supplied to the USB power reception apparatus via the bus line,

and wherein the controller controls the reference voltage based on a detection result obtained by the current detection unit in addition to the detection result obtained by the bus voltage detection unit.

10. The USB power supply apparatus according to claim 3, wherein the controller further comprises an output voltage detection unit that detects an output voltage of the power supply circuit,

and wherein the controller controls the reference voltage based on a detection result obtained by the output voltage detection unit in addition to the detection result obtained by the bus voltage detection unit.

11. The USB power supply apparatus according to claim 1, wherein the controller comprises a current detection unit that detects a supply current supplied to the USB power reception apparatus via the bus line,

and wherein the controller controls the reference voltage based on a detection result obtained by the current detection unit.

12. The USB power supply apparatus according to claim 1, wherein the controller comprises a voltage drop detection unit that detects a difference between an output voltage of the power supply circuit and a bus voltage at a position that is closer to the USB power reception apparatus side than the switch,

and wherein the controller controls the reference voltage based on a detection result obtained by the voltage drop detection unit.

13. The USB power supply apparatus according to claim 11, wherein the reference voltage is configured as a voltage obtained by superimposing a correction voltage on a predetermined setting voltage,

and wherein the controller adjusts the correction 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 than the USB power reception apparatus side than the switch.

14. The USB power supply apparatus according to claim 13, wherein the controller further comprises a communication unit that communicates with the USB power reception apparatus,

and wherein the controller determines the setting voltage based on negotiation with the USB power reception apparatus.

15. The USB power supply apparatus according to claim 1, that conforms to the USB-PD (Power Delivery) specification, further comprising an inductor provided at a position that is closer to the USB power reception apparatus side than the switch,

wherein the controller controls the reference voltage so as to reduce an amount of voltage drop 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 inductor.

16. The USB power supply apparatus according to claim 1, that conforms to the USB-PD (Universal Serial Bus-Power Delivery) specification or otherwise the USB Type-C specification.

17. An electronic device comprising the USB power reception apparatus according to claim 1.

18. A control method for controlling a USB power supply apparatus that conforms to the USB (Universal Serial Bus) specification, and that supplies an electric power to a USB power reception apparatus, wherein the USB power supply apparatus comprises:

a power supply circuit;

a bus line that connects an output of the power supply circuit and the USB power reception apparatus; and

a switch provided on a path of the bus line,

and wherein the control method comprises;

feedback controlling the power supply circuit such that an output voltage of the power supply circuit approaches a reference voltage; and

adaptively controlling the reference voltage according to an electrical state of the USB power supply apparatus.

19. The control method according to claim 18, wherein the control comprises:

detecting a bus voltage at a position that is closer to the USB power reception apparatus side than the switch; and

adjusting the reference voltage based on the bus voltage thus detected.

20. The control method according to claim 19, wherein adjusting the reference voltage comprises controlling the reference voltage such that the bus voltage at a position that is closer to the USB power reception apparatus side than the switch approaches a predetermined setting voltage.

21. The control method according to claim 18, wherein the control comprises:

detecting a supply current which is supplied to the USB power reception apparatus via the bus line; and

adjusting the reference voltage based on the supply current thus detected.