Regulated power supply with multiple regulators sharing the total current supplied to a load

• US 20070200538A1
• Filed: 02/28/2006
• Published: 08/30/2007
• Est. Priority Date: 02/28/2006
• Status: Active Grant

• Current Assignee: Infineon Technologies Austria Ag (Infineon Technologies AG)
• Original Assignee: Infineon Technologies Austria Ag (Infineon Technologies AG)
• Inventors: Tang, Benjamin, Southwell, Scott, Ostrom, Kenneth
• Granted Patent: US 8,008,901 B2
• Time in Patent Office: Days
• US Class Current: 323/237
• CPC Class Codes: H02M 3/157 with digital control
• CPC Class Codes: H02M 3/158 including plural semiconductor devices as final control devices for a single load
• CPC Class Codes: H02M 3/1584 with a plurality of power processing stages connected in parallel

Abstract

Disclosed is a digital current sharing structure and method in which a plurality of regulators are configured to share the load current. Current share circuits in each of the regulators are configured to measure and compare the average current provided by that particular regulator with the overall average current provided by all the regulators. Each of the current share circuits then provides an output so that the output of each regulator is adjusted to provide the same amount of current to the load. Digital processing with both analog and digital averaging are disclosed. Also disclosed is a programmable hysteresis technique to eliminate relatively trivial adjustments.

Claims

1. A regulated power supply comprising:

a first regulator having an output coupled to a load and supplying current to the load during a first phase;

a second regulator having an output coupled to the load and supplying current to the load during a second phase;

a first current share circuit coupled to the load for measuring the average current provided to the load during the first phase;

a second current share circuit coupled to the load for measuring the average current provided to the load during the second phase;

circuitry in each of said first and second current share circuits for determining the overall average current to be shared by the regulators; and

compare circuits for comparing each of the average currents provided to the load during each of the first and second phases, respectively, with the overall average current to be shared by the regulators.

2. The regulated power supply as in claim 1 wherein:

the compare circuits provide an output signal to adjust the current output of one of the first and second regulators.

3. The regulated power supply as in claim 2 wherein:

the compare circuits provide an output signal to adjust the current output of either the first regulator or the second regulator only when the difference in the compared outputs exceeds a predetermined value.

4. The regulated power supply as in claim 1, wherein:

the first and second current share circuits and the circuitry in each of said first and second current share circuits for determining the average current to be shared by the regulators are digital.

5. The regulated power supply as in claim 4, further comprising:

a plurality of regulators connected in a daisy chain configuration.

6. A regulated power supply as in claim 1 further comprising:

a current mirror in each of said regulators.

7. A regulated power supply as in claim 1 further comprising:

an inductor coupled between the output of each of the regulators and the load; and

a circuit in parallel with each said inductor.

33. A regulated power supply as in claim 1 wherein:

each of said regulators is a multiphase buck regulator.

34. A regulated power supply as in claim 1 wherein said first and second current share circuits are coupled by means of first and second conductors, the first conductor providing an input and the second conductor providing an output.

35. A regulated power supply as in claim 34, wherein the first conductor of the first current share circuit is coupled to the second conductor of the second current share circuit.

37. A regulated power supply as in claim 1, wherein said first and second current share circuits are coupled by means of first and second conductors and comprising:

a capacitor connected to the first conductor at a first node and to said second conductor at a second node.

38. A regulated power supply as in claim 37, wherein:

said first node is a common summation node for determining the average current.

8. A method of balancing the current supplied by each one of a plurality of regulators coupled to a load, comprising the steps of:

measuring the average load current supplied by each regulator;

determining the overall average current to be shared by the regulators;

comparing each of the average load currents with the overall average current to be shared by the regulators; and

adjusting the output current of each regulator to supply the same current.

9. A method of balancing the current supplied by each one of a plurality of regulators coupled to a load, as in claim 8, wherein:

each of said regulators has an active phase occurring at a different time and said step of measuring the average load current supplied by each regulator occurs during the active phase of each regulator.

10. A method of balancing the current supplied by each one of a plurality of regulators coupled to a load, as in claim 9 wherein the step of comparing each of the average load currents with the overall average current to be shared by the regulators is performed by analog comparators that provide a binary up or down signal based on the relative amplitude of the compared current values.

11. A method of balancing the current supplied by each one of a plurality of regulators coupled to a load, as in claim 10 wherein the analog comparators provide a binary up or down signal only if the difference between the amplitudes of the compared current values exceeds a predetermined amount.

12. A method of balancing the current supplied by each one of a plurality of regulators coupled to a load, as in claim 9 wherein the step of comparing each of the average load currents with the overall average current to be shared by the regulators is performed by digital comparators that provide a binary up or down signal based on the relative amplitude of the compared current values.

13. A method of balancing the current supplied by each one of a plurality of regulators coupled to a load, as in claim 12 wherein the digital comparators provide a binary up or down signal only if the difference between the amplitudes of the compared current values exceeds a predetermined amount.

14. The method of balancing the current supplied by each one of a plurality of regulators coupled to a load as in claim 8, wherein the step of determining the overall average current to be shared by the regulators is performed iteratively.

15. A method of balancing the current supplied by each one of a plurality of regulators coupled to a load, as in claim 8, wherein the step of measuring the average load current supplied by each regulator includes the step of:

sensing the current with a lossless technique.

16. A method of balancing the current supplied by each one of a plurality of regulators coupled to a load, as in claim 15, wherein the step of sensing the current with a lossless technique comprises:

sensing the current with a current mirror,

17. A method of balancing the current supplied by each one of a plurality of regulators coupled to a load, as in claim 15, wherein each one of the plurality of regulators has an inductor at its output and the step of sensing the current with a lossless technique comprises:

sensing the current with a capacitor coupled in parallel with the incuctor.

18. A regulated power supply comprising:

a first regulator having a first current share circuit and having an output coupled to a load,

a second regulator having a second current share circuit and also having an output coupled to said load;

said first and second current share circuits being coupled to each other, thereby balancing the current provided by said first and second regulators.

19. A regulated power supply as in claim 18 wherein said first and second current share circuits are coupled by means of first and second conductors, the first conductor providing an input and the second conductor providing an output.

20. A regulated power supply as in claim 19, wherein the first conductor of the first current share circuit is coupled to the second conductor of the second current share circuit.

21. A regulated power supply as in claim 19, wherein the first conductor of said first current share circuit and the first conductor of said second current share circuit are coupled.

22. A regulated power supply as in claim 18 further comprising:

a current mirror in each of said regulators.

23. A regulated power supply as in claim 18, wherein each of said regulators has an inductor at its output and further comprising:

a capacitor coupled in parallel to the inductor in each of said regulators.

24. A regulated power supply as in claim 18, wherein each of said current share circuits comprise:

compare circuits for comparing the overall average current value with the current value supplied by the regulator.

25. The regulated power supply as in claim 24 wherein:

the compare circuits provide an output signal to adjust the current output of either the first regulator or the second regulator.

26. The regulated power supply as in claim 18 wherein:

the compare circuits provide an output signal to adjust the current output of either the first regulator or the second regulator only when the difference in the compared outputs exceeds a predetermined value.

27. The regulated power supply as in claim 18, wherein:

the first and second current share circuits and the circuitry in each of said first and second current share circuits for determining the average current to be shared by the regulators are digital.

28. The regulated power supply as in claim 27, further comprising:

a plurality of regulators connected in a daisy chain configuration.

29. A regulated power supply as in claim 18 further comprising:

an inductor coupled between each of the regulators and the load; and

a circuit in parallel with each said inductor.

30. A regulated power supply as in claim 18 wherein:

each of said regulators is a multiphase buck regulator.

31. A regulated power supply as in claim 18, wherein said first and second current share circuits are coupled by means of first and second conductors and comprising:

a capacitor connected to the first conductor at a first node and to said second conductor at a second node.

32. A regulated power supply as in claim 31, wherein:

said first node is a common summation node for determining the average current.

36. A regulated power supply as in claim 31, wherein the first conductor of said first current share circuit and the first conductor of said second current share circuit are coupled.