Controlling switching circuits to balance power or current drawn from multiple power supply inputs

• US 20070281755A1
• Filed: 06/01/2006
• Published: 12/06/2007
• Est. Priority Date: 06/01/2006
• Status: Active Grant

• Current Assignee: Analog Devices International Unlimited Company (Analog Devices, Inc.)
• Original Assignee: Linear Technology Corporation (Analog Devices, Inc.)
• Inventors: Dwelley, David McLean
• Granted Patent: US 9,705,325 B2
• Time in Patent Office: Days
• US Class Current: 455/572
• CPC Class Codes: H02J 1/102 being switching converters H02J1/108, H02J1/12 take precedence

Abstract

Novel techniques for balancing power or current drawn from multiple power supply inputs by controlling switching circuits associated with the respective power supply inputs. Each switching circuit may be controlled so as to limit current in its transformer or inductor in each switching cycle to a peak or average current value common to all switching circuits.

Claims

1. A power supply circuit comprising:

multiple power supply inputs,

multiple switching circuits coupled to the respective power supply inputs,

at least one inductive component associated with the switching circuits, and

control circuitry for controlling the switching circuits so as to limit current in said at least one inductive component in each switching cycle to a current value common to all of the switching circuits.

2. The circuit of claim 1, wherein the control circuitry is configured for controlling the switching circuits so as to limit the current in said at least one inductive component in each switching cycle to a peak current value common to all of the switching circuits.

3. The circuit of claim 1, wherein the control circuitry is configured for controlling the switching circuits so as to limit the current in said at least one inductive component in each switching cycle to an average current value common to all of the switching circuits.

4. The circuit of claim 1, wherein the control circuitry is configured to balance power drawn from each of the power supply inputs.

5. The circuit of claim 1, wherein the control circuitry is configured to balance current drawn from each of the power supply inputs.

6. The circuit of claim 1, wherein the inductive component includes a transformer.

7. The circuit of claim 6, wherein a separate transformer is associated with each of the switching circuits.

8. The circuit of claim 6, wherein the switching circuits share a common transformer.

9. The circuit of claim 1, wherein the inductive component includes an inductor.

10. The circuit of claim 1, wherein each of the switching circuits includes a switching regulator.

11. The circuit of claim 10, wherein the switching regulator has a flyback configuration.

12. The circuit of claim 10, wherein the control circuitry includes comparator circuitry for comparing a value corresponding to current in each of the switching circuits with a preset threshold value common to all switching circuits.

13. The circuit of claim 12, wherein the preset threshold value is selected to limit current in said at least one inductive component associated with the switching circuits.

14. The circuit of claim 12, wherein the control circuitry further includes logic circuitry responsive to an output of the comparator circuitry and controlled by a clock signal common to all of the switching circuits for producing multiple control signals for controlling the respective switching circuits.

15. The circuit of claim 14, wherein the comparator circuitry includes multiple comparators corresponding to the respective switching circuits, and the logic circuitry includes multiple logic circuits responsive to the respective comparators for controlling switching of the respective switching circuits.

16. The circuit of claim 14, wherein the comparator circuitry includes a single comparator for comparing a current value common to all of the switching circuits with the threshold value, and a logic circuit responsive to an output of the comparator for producing multiple control signals for controlling switching of the respective switching circuits.

17. The circuit of claim 14, wherein the control circuitry further includes an integrator responsive to current in each of the switching circuits for providing the comparator circuitry with a current value integrated over a switching cycle.

18. The circuit of claim 14, wherein the logic circuitry is configured for producing interleaving control signals so as to turn on only one of the switching circuits at a time.

19. The circuit of claim 10, wherein the switching regulator has a buck configuration.

20. The circuit of claim 19, wherein the control circuitry includes differential-to-single-ended converters for converting differential signals sensed at the power supply inputs to single-ended signals.

21. The circuit of claim 20, wherein the control circuitry further includes comparators for comparing the single-ended signals with a common threshold value selected to limit current in said at least one inductive component.

22. The circuit of claim 21, wherein the control circuitry further includes pulse-width-modulation circuits responsive to outputs of the comparators for controlling switching of the switching circuits.

23. The circuit of claim 10, wherein the switching regulator has a boost configuration.

24. The circuit of claim 23, wherein the control circuitry includes comparators for comparing signals sensed at the power supply inputs with a common threshold value selected to limit current in said at least one inductive component.

25. The circuit of claim 24, wherein the control circuitry further includes pulse-width-modulation circuits responsive to outputs of the comparators for controlling switching of the switching circuits.

26. A system for supplying power to a powered device over a communication link having a first wire set and a second wire set, the system comprising signal balancing circuitry for balancing signals supplied to the powered device from the first and second wire sets,

the signal balancing circuitry includes:

first and second switching circuits respectively coupled to the first and second wire sets for providing power to the powered device,

at least one inductive component associated with the first and second switching circuits, and

control circuitry for controlling the switching circuits so as to limit current in said at least one inductive component in each switching cycle to a current value common to the first and second switching circuits.

27. The system of claim 26, wherein the signal balancing circuit is configured to balance power drawn by the powered device from the first and second wire sets.

28. The system of claim 26, wherein the signal balancing power is configured to balance current drawn by the powered device from the first and second wire sets.

29. The circuit of claim 26, wherein the control circuitry is configured for controlling the switching circuits so as to limit the current in said at least one inductive component in each switching cycle to a peak current value common to all of the switching circuits.

30. The circuit of claim 26, wherein the control circuitry is configured for controlling the switching circuits so as to limit the current in said at least one inductive component in each switching cycle to an average current value common to all of the switching circuits.

31. The circuit of claim 26, wherein the inductive component includes a transformer.

32. The circuit of claim 31, wherein a separate transformer is provided for each of the switching circuits.

33. The circuit of claim 31, wherein a common transformer is shared by the switching circuits.

34. The circuit of claim 26, wherein the inductive component includes an inductor.

35. The system of claim 26, wherein each of the first and second wire sets is composed of two pairs of conductors.

36. The system of claim 26, wherein the communication link includes Ethernet cabling.

38. The method of claim 33, wherein each of the switching circuit is turned off when a respective signal value reaches the preset threshold value.

37. A method of balancing signals supplied by multiple power supply inputs, comprising the steps of:

converting signals supplied from the power supply inputs using respective switching circuits associated with at least one inductive component, and

comparing signal values in the switching circuits with a preset threshold value common to all of the switching circuits to limit current in said at least one inductive component in each switching cycle to a common current value.