Power switching in a two-wire conductor system

• US 9,772,665 B2
• Filed: 12/11/2013
• Issued: 09/26/2017
• Est. Priority Date: 10/05/2012
• Status: Active Grant

• Current Assignee: Analog Devices, Inc.
• Original Assignee: Analog Devices, Inc.
• Inventors: Patterson, Stuart
• Primary Examiner(s): Fureman, Jared
• Assistant Examiner(s): Bukhari, Aqeel
• Application Number:
  US14/102,603
• Publication Number:
  US 20140101477A1
• Time in Patent Office: 1,385 Days
• Field of Search: None
• CPC Class Codes: G06F 1/263 Arrangements for using multiple switchable power supplies, e.g. battery and AC G06F1/30 takes precedence
• CPC Class Codes: G06F 1/266 Arrangements to supply power to external peripherals either directly from the computer or under computer control, e.g. supply of power through the communication port, computer controlled power-strips
• CPC Class Codes: G06F 1/28 Supervision thereof, e.g. detecting power-supply failure by out of limits supervision
• CPC Class Codes: G06F 13/4256 using a clocked protocol

Abstract

In an example embodiment, a power switching circuit of an automobile audio bus (A²B) chip is provided in a bi-directional, multi-node two-wire conductor system that includes a plurality of A²B chips interconnected on a twisted wire pair bus (A²B bus), with at least one A²B chip functioning as a master and the remaining A²B chips functioning as slaves. The power switching circuit of the A²B chip powers up a next downstream A²B chip in the A²B bus sequentially according to a power switching procedure, and the power switching circuit is configured to detect faults in the A²B bus before, during, and after the power switching procedure. Each A²B chip enables power to the next downstream A²B chip without risk of damage to any components in the system due to line faults on the downstream A²B bus, or collapse of the power supply at the local A²B chip.

Claims

1. A power switching circuit of a communication device for use in a bi-directional two-wire communication system, comprising:

an upstream coupling circuit to couple the communication device to an upstream communication device via an upstream pair of wires, wherein the upstream coupling circuit is to receive data and power from an electrical signal transmitted to the communication device from the upstream communication device over the upstream pair of wires; and

a downstream coupling circuit to couple the communication device to a downstream communication device via a downstream pair of wires, wherein the downstream coupling circuit is to provide data and power over the downstream pair of wires to the downstream communication device according to a nominal power switching procedure;

wherein the power switching circuit is to detect one or more faults in the communication system before, during and after the nominal power switching procedure, and to modify the nominal power switching procedure in response to detection of one or more faults; and

wherein the nominal power switching procedure includes a gradual increase of current provided to the downstream pair of wires.

2. The power switching circuit of claim 1, wherein the downstream coupling circuit is to sense a condition of the downstream pair of wires before, during, and after the nominal power switching procedure, and to provide feedback to a switch control mechanism.

3. The power switching circuit of claim 2, wherein, under the nominal power switching procedure, the downstream coupling circuit is to gradually charge the downstream pair of wires and the downstream communication device over a bounded charging time simultaneously with preservation of local power and data communication.

4. The power switching circuit of claim 3, wherein the power switching circuit is to maintain a local power supply voltage during the nominal power switching procedure.

5. The power switching circuit of claim 1, wherein the downstream coupling circuit is to enable power to the downstream communication device in response to a command from a master communication device upstream of the communication device.

6. The power switching circuit of claim 1, wherein the power switching circuit is to complete the nominal power switching procedure if no faults are detected.

7. The power switching circuit of claim 1, comprising:

a power switch to isolate the communication device from the downstream communication device;

a diagnostic module comprising a plurality of sense comparators to detect one or more faults in the communication system before, during, and after the nominal power switching procedure;

a control logic to control a current source to dynamically adapt a charging current to a load on the downstream pair of wires until a pre-determined charging rate is achieved; and

a local power regulator to provide feedback on a status of a local power supply at the communication device.

8. The power switching circuit of claim 7, wherein the current source comprises a current controlled switching element.

9. The power switching circuit of claim 7, wherein the control logic comprises a digital circuit.

10. The power switching circuit of claim 7, wherein the control logic is to control the power switch through a switch driver.

11. The power switching circuit of claim 7, wherein the power switch is located on a positive side of a power supply line decoupled from a data line in the communication device, and wherein the current source is located on a negative side of the power supply line.

12. The power switching circuit of claim 11, wherein the current source is integrated into a chip of the communication device, the chip including the control logic, and the power switch is located outside the chip.

13. The power switching circuit of claim 11, wherein the current source is located outside a chip of the communication device, the chip including the control logic, and the power switch is integrated into the chip.

14. The power switching circuit of claim 7, wherein the diagnostic module includes an excitation module to excite the downstream pair of wires with either voltage or current, and wherein the sense comparators detect the excitation if no fault exists on the downstream pair of wires.

15. A power switching method executed by a communication device in a bi-directional two-wire communication system, the method comprising:

receiving data and power from an electrical signal transmitted to the communication device from an upstream communication device over an upstream pair of wires;

providing data and power over a downstream pair of wires to a downstream communication device in accordance with a nominal power switching procedure, wherein the nominal power switching procedure includes a gradual increase of current provided to the downstream pair of wires;

detecting one or more faults in the communication system before, during, or after the nominal power switching procedure; and

modifying the nominal power switching procedure in response to detecting the one or more faults.

16. The power switching method of claim 15, wherein the nominal power switching procedure includes:

turning on a current source of the power switching circuit at a lowest setting of charging current;

monitoring a rate of settling of current in the communication system;

detecting a status of a local power supply at the communication device; and

increasing the charging current if the rate of settling is higher than a pre-determined threshold, and the local power supply is viable, until a pre-determined charging rate is reached.

17. The power switching method of claim 15, wherein the nominal power switching procedure includes:

determining whether the downstream pair of wires is fully charged.

18. The power switching method of claim 15, wherein detecting one or more faults includes:

exciting the downstream pair of wires with voltage or current to detect destructive faults.

19. The power switching method of claim 15, wherein the nominal power switching procedure includes:

setting a first flag high to indicate start of power switching;

setting a second flag high to indicate completion of power switching; and

setting a third flag high to indicate a fault.