VARYING OPERATION OF A VOLTAGE REGULATOR, AND COMPONENTS THEREOF, BASED UPON LOAD CONDITIONS

• US 20110062930A1
• Filed: 11/23/2010
• Published: 03/17/2011
• Est. Priority Date: 04/10/2008
• Status: Active Grant

• Current Assignee: Intersil Americas LLC (Renesas Electronics Corporation)
• Original Assignee: Intersil Americas LLC (Renesas Electronics Corporation)
• Inventors: Saunders, Christopher S., Houston, Michael J.
• Granted Patent: US 8,125,207 B2
• Time in Patent Office: Days
• US Class Current: 323/284
• CPC Class Codes: H02M 1/0032 Control circuits allowing low power mode operation, e.g. in standby mode
• CPC Class Codes: H02M 3/1584 with a plurality of power processing stages connected in parallel
• CPC Class Codes: H02M 3/1588 comprising at least one synchronous rectifier element H02M3/1582, H02M3/1584 take precedence
• CPC Class Codes: Y02B 70/10 Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes

Abstract

A method for operating a voltage regulator controller, for use in a voltage regulator including coupled inductors, is provided as follows. A first signal is generated for driving a first switch of the voltage regulator. A second signal is generated driving a first switch of the voltage regulator. The voltage regulator determines whether a light-load condition exists. Upon determining the existence of a light-load condition, adjusting the phase difference between said first and second signals so that the first and second signals are approximately in-phase.

Claims

1. A controller for a voltage regulator, comprising:

a first controller to generate a first signal to drive a first switch of the voltage regulator;

a second controller to generate a second signal to drive a second switch of the voltage regulator; and

a comparator coupled to an output of the voltage regulator, an input of the first controller and an input of the second controller, wherein the comparator is operable to determine if a light-load condition exists, and if a light-load condition exists, generate a third signal to adjust a phase difference between the first signal and the second signal so that the first signal and the second signal are approximately in-phase.

2. The controller of claim 1, wherein the first switch comprises a transistor switch.

3. The controller of claim 1, further comprising a generator and phase shift controller coupled to an output of the comparator, the input of the first controller and the input of the second controller.

4. The controller of claim 1, wherein if a light-load condition does not exist, the comparator is further operable to generate a fourth signal to adjust the phase difference so that the first signal and the second signal are substantially out-of-phase.

5. The controller of claim 1, wherein the first signal comprises a Pulse Width Modulated (PWM) signal.

6. The controller of claim 1, wherein one input of the comparator is coupled to an output current of the voltage regulator, and a second input of the comparator is coupled to a threshold current source.

7. A voltage regulator, comprising:

a first controller to generate a first signal;

a second controller to generate a second signal;

a switch to receive the first signal at a first input and the second signal at a second input;

a first inductor coupled to a first output of the switch;

a second inductor coupled to a second output of the switch, the first inductor and second inductor inductively coupled; and

a comparator, a first input of the comparator coupled to receive a signal indicative of a current in the first inductor and a signal indicative of a current in the second inductor, a second input of the comparator coupled to receive a threshold current signal, and an output of the comparator coupled to a third input of the switch, wherein the comparator is operable to compare a value of the signal indicative of the current in the first inductor and the signal indicative of the current in the second inductor with a value of the threshold current signal to determine if a light-load condition exists, and if a light-load condition exists, generate a third signal to cause the switch to switch at least one of the first signal and the second signal so that a signal at the first output of the switch is approximately in-phase with a signal at the second output of the switch.

8. The voltage regulator of claim 7, wherein the light-load condition exists if the value of the signal indicative of the current in the first inductor and the signal indicative of the current in the second inductor is less than the value of the threshold current signal.

9. The voltage regulator of claim 7, wherein the switch comprises a single pole, double throw switch.

10. The voltage regulator of claim 7, further comprising:

a first current sensor coupled to the first inductor;

a second current sensor coupled to the second inductor; and

a summer, wherein a first input of the summer is coupled to the first current sensor, a second input of the summer is coupled to the second current sensor, and an output of the summer is coupled to the first input of the comparator.

11. The voltage regulator of claim 7, wherein the signals indicative of the current in the first inductor and the second inductor represent a load current for the voltage regulator.

12. A system, comprising:

a voltage regulator;

a power source coupled to an input of the voltage regulator; and

a load coupled to an output of the voltage regulator, the voltage regulator including;

a first controller to generate a first signal to drive a first switch of the voltage regulator;

a second controller to generate a second signal to drive a second switch of the voltage regulator; and

a comparator coupled to an output of the voltage regulator, an input of the first controller and an input of the second controller, wherein the comparator is operable to determine if a light-load condition exists, and if a light-load condition exists, generate a third signal to shift a phase of at least one of the first signal and the second signal so that a phase difference between the first signal and the second signal is approximately zero degrees.

13. The system of claim 12, wherein the load comprises at least one of a processor, a memory, and a bus.

14. The system of claim 12, wherein if a light-load condition does not exist, the comparator is further operable to generate a fourth signal to shift the phase of the at least one of the first signal and the second signal so that the phase difference between the first signal and the second signal is substantially greater than zero degrees.

15. A method for controlling a voltage regulator, comprising:

generating a first drive signal for a first phase of the voltage regulator;

generating a second drive signal for a second phase of the voltage regulator;

sensing a first current flowing through the first phase of the voltage regulator;

sensing a second current flowing through the second phase of the voltage regulator;

summing the first sensed current and the second sensed current;

comparing a value of the sum with a threshold value; and

if the sum is less than the threshold value, adjusting a phase difference between the first drive signal and the second drive signal so that the first drive signal and the second drive signal are approximately in-phase.

16. The method of claim 15, wherein if the sum is not less than the threshold value, adjusting the phase difference between the first drive signal and the second drive signal so that the first drive signal and the second drive signal are substantially out-of-phase.

17. The method of claim 15, further comprising inductively coupling a first inductor in the first phase to a second inductor in the second phase.

18. The method of claim 15, wherein the adjusting comprises generating a phase-shift control signal.

19. The method of claim 15, wherein the generating the first drive signal comprises generating a PWM signal.

20. The method of claim 15, wherein the comparing comprises comparing a value of a load current with the threshold value.

21. A system, comprising:

a voltage regulator having at least two phases;

a power source coupled to an input of the voltage regulator; and

a load coupled to an output of the voltage regulator, the voltage regulator including;

a first controller to generate a first signal;

a second controller to generate a second signal; and

a comparator coupled to an output of the voltage regulator, wherein the comparator is operable to determine if a light-load condition exists, and if a light-load condition exists, generate a third signal so that that the voltage regulator uses at least one of the first signal and the second signal to provide in-phase signals to drive the at least two phases and provide the output for the load.

22. The system of claim 21, wherein generating a third signal comprises generating a signal that adjusts the phase of at least one of the first and second signals to be approximately in-phase.

23. The system of claim 21, wherein generating a third signal comprises generating a signal that selects one of the first signal and the second signal to drive the at least two phases.

24. A method for controlling a voltage regulator having at least two phases, comprising:

generating a first drive signal for the voltage regulator;

generating a second drive signal for the voltage regulator;

determining whether a light-load condition exists; and

if a light load condition exists, driving the at least two phases the first drive signal and the second drive signal so that the first drive signal and the second drive signal are approximately in-phase.