Multiphase power regulator with load adaptive phase control

• US 8,193,796 B2
• Filed: 02/16/2009
• Issued: 06/05/2012
• Est. Priority Date: 07/03/2006
• Status: Active Grant

• Current Assignee: Infineon Technologies Austria Ag (Infineon Technologies AG)
• Original Assignee: Infineon Technologies Austria Ag (Infineon Technologies AG)
• Inventors: Tang, Benjamim, Carroll, Robert T., Steffen, Nicholas R., Pierson, Richard C.
• Primary Examiner(s): Berhane, Adolf
• Assistant Examiner(s): PHAM, EMILY P
• Application Number:
  US12/371,835
• Publication Number:
  US 20090224731A1
• Time in Patent Office: 1,205 Days
• Field of Search: 323/271, 323/272, 323/283, 323/284, 323/285, 307/80, 307/81, 307/85, 307/86, 307/87
• US Class Current: 323/283
• CPC Class Codes: H02M 1/0012 Control circuits using digital or numerical techniques in DC/DC converters H02M3/157, H02M3/33515; in DC-AC converters H02M7/53873
• CPC Class Codes: H02M 3/1584 with a plurality of power processing stages connected in parallel

Abstract

Disclosed is a power regulator for providing precisely regulated power to a microelectronic device such as a microprocessor. Improved power regulation is accomplished by optimizing the power efficiency of the power regulator. In particular, in a multiphase system, the number of active phases is increased or decreased to achieve optimum power efficiency. The multiphase voltage regulator adapts the operating mode to maximize efficiency as the load current demand of the load device changes by adjusting the number of active phases to maximize efficiency. The total value of current provided by the regulator and the total number of active phases is determined, the total number of active phases is compared with the number of active phases required to provide the total value of current at maximum efficiency; and the number of active phases is adjusted to provide the total value of current at maximum efficiency.

A current sense circuit senses the current at each phase, a summing circuit coupled to the output of the current sense circuit provides the total current value of all the measured phases, a circuit coupled to the output of the summing circuit provides the time averaged total current value to a threshold detecting circuit that determines the number of phases at which the voltage regulator should be operating for maximum efficiency, and a circuit for comparing the number of phases that are operating to the number of phases at which the voltage regulator should be operating adjusts the number of active phases to the number of phases at which the voltage regulator should be operating for maximum efficiency.

Claims

1. A multiphase voltage regulator, comprising:

a plurality of phases, wherein each phase is configured to be enabled and disabled; and

a controller configured to adjust the number of enabled phases according to an optimal number of phases for substantially maximum efficiency based on an output condition, including being configured to slow drop an enabled phase, wherein the controller is further configured to;

receive a phase current from each enabled phase and output a total current;

produce a time averaged total current based on the total current;

compare the time averaged total current to a plurality of thresholds to determine an optimal number of phases; and

compare the number of enabled phases with the optimal number of phases and output a phase control signal.

2. A multiphase voltage regulator as in claim 1, wherein the controller is further configured to adjust a non-overlap time on each enabled phase.

3. A multiphase voltage regulator as in claim 1, wherein the threshold detecting circuit comprises a plurality of comparator circuits.

4. A multiphase voltage regulator as in claim 1, wherein the controller further comprises:

a slow drop circuit;

a slow add circuit; and

a fast add circuit;

wherein the slow drop circuit, the slow add circuit, and the fast add circuit are coupled to the threshold detecting circuit and provide outputs configured to determine a speed at which to adjust the number of enabled phases.

5. A multiphase voltage regulator as in claim 4, wherein the slow drop circuit comprises:

a counter configured to generate a count of a number of consecutive clock cycles the number of enabled phases exceeds the optimal number of phases for substantially maximum efficiency; and

a comparator circuit configured to receive the output of the counter and generate a drop slow signal that is outputted to a state machine.

6. A multiphase voltage regulator as in claim 4, wherein the slow drop circuit comprises:

a plurality of counters configured to generate a count of a number of clock cycles a phase level signal indicates a phase should be dropped; and

a plurality of comparators configured to compare the counts generated to a threshold and output a phase drop signal for each phase that exceeds the threshold.

7. A multiphase voltage regulator as in claim 4, wherein the slow add circuit comprises:

a counter configured to generate a count of a number of consecutive times the number of enabled phases is below the optimal number of phases for substantially maximum efficiency; and

a comparator circuit configured to receive the output of the counter and generate an add slow signal that is outputted to a state machine.

8. A multiphase voltage regulator as in claim 4, wherein the fast add circuit comprises a comparator configured to generate a signal to turn all phases on when a threshold is exceeded.

9. A multiphase voltage regulator as in claim 8, wherein the fast add circuit further comprises an ATR input, wherein the fast add circuit is further configured to generate the signal to turn all phases on during an ATR event.

10. A method of adjusting a number of enabled phases in a multiphase voltage regulator, comprising:

measuring an output current;

adjusting the number of enabled phases to an optimal number of phases for substantially maximum efficiency based on an output condition, including slow dropping an enabled phase by;

receiving a phase current from each enabled phase and outputting a total current;

producing a time averaged total current based on the total current;

comparing the time averaged total current to a plurality of thresholds to determine an optimal number of phases; and

comparing the number of enabled phases with the optimal number of phases and outputting a phase control signal.

11. A method of adjusting the number of enabled phases in a multiphase voltage regulator as in claim 10, wherein slow dropping an enabled phase comprises dropping an enabled phases one at a time until the optimal number of phases is reached.

12. A method of adjusting the number of enabled phases in a multiphase voltage regulator as in claim 10, comprising directly dropping enabled phases.

13. A method of adjusting the number of enabled phases in a multiphase voltage regulator as in claim 10, wherein adjusting the number of enabled phases to the optimal number of phases further comprises activating additional phases slowly.

14. A method of adjusting the number of enabled phases in a multiphase voltage regulator as in claim 10, wherein adjusting the number of enabled phases to the optimal number of phases further comprises adjusting a non-overlap time on each enabled phase.

15. A method of adjusting the number of enabled phases in a multiphase voltage regulator as in claim 10, wherein adjusting the number of enabled phases to the optimal number of phases further comprises activating additional phases quickly.

16. A method of adjusting the number of enabled phases in a multiphase voltage regulator as in claim 15, wherein activating additional phases quickly comprises activating additional phases quickly when a transient amplitude passes a threshold.

17. A multiphase voltage regulator, comprising:

a plurality of phases configured to be enabled and disabled;

a current sense circuit configured to measure a load current; and

a controller configured to adjust the number of enabled phases to an optimal number of phases for substantially maximum efficiency based on the load current, the controller comprising;

an adder circuit configured to receive a phase current from each enabled phase and output a total current;

an averaging circuit configured to receive the total current and produce a time averaged total current;

a threshold detecting circuit configured to compare the time averaged total current to a plurality of thresholds to determine an optimal number of phases; and

a comparison circuit configured to compare the number of enabled phases with the optimal number of phases and output a phase control signal.

18. A multiphase voltage regulator as in claim 17, wherein the controller further comprises:

a slow drop circuit;

a slow add circuit; and

a fast add circuit;

wherein the slow drop circuit, the slow add circuit, and the fast add circuit are coupled to the threshold detecting circuit and provide outputs configured to determine a speed at which to adjust the number of enabled phases.

19. A multiphase voltage regulator as in claim 18, wherein the slow drop circuit comprises:

a counter configured to generate a count of a number of consecutive clock cycles the number of enabled phases exceeds the optimal number of phases for substantially maximum efficiency; and

a comparator circuit configured to receive the output of the counter and generate a drop slow signal that is outputted to a state machine.

20. A multiphase voltage regulator as in claim 18, wherein the slow drop circuit comprises:

a plurality of counters configured to generate a count of a number of clock cycles a phase level signal indicates a phase should be dropped; and

a plurality of comparators configured to compare the counts generated to a threshold and output a phase drop signal for each phase that exceeds the threshold.

21. A multiphase voltage regulator as in claim 18, wherein the slow add circuit comprises:

a counter configured to generate a count of the number of consecutive clock cycles the number of enabled phases is below the optimal number of phases for substantially maximum efficiency; and

a comparator circuit configured to receive the output of the counter and generate an add slow signal that is outputted to a state machine.

22. A multiphase voltage regulator as in claim 18, wherein the controller is further configured to adjust a non-overlap time on each enabled phase.

23. A multiphase voltage regulator as in claim 18, wherein the fast add circuit comprises a comparator configured to generate a signal to turn all phases on when a threshold is exceeded.

24. A multiphase voltage regulator as in claim 23, wherein the fast add circuit further comprises an ATR input, wherein the fast add circuit is further configured to generate the signal to turn all phases on during an ATR event.