Apparatus and method for a voltage booster with improved voltage regulator efficiency

• US 6,937,487 B1
• Filed: 04/29/2003
• Issued: 08/30/2005
• Est. Priority Date: 04/29/2003
• Status: Active Grant

• Current Assignee: National Semiconductor Corporation (Texas Instruments, Inc.)
• Original Assignee: National Semiconductor Corporation (Texas Instruments, Inc.)
• Inventors: Bron, Ernest Armand
• Primary Examiner(s): Laxton, Gary L
• Application Number:
  US10/427,004
• Time in Patent Office: 854 Days
• Field of Search: 363/59, 363/60, 327/535, 327/536, 323/266
• US Class Current: 363/60
• CPC Class Codes: H02M 1/0045 Converters combining the concepts of switch-mode regulation and linear regulation, e.g. linear pre-regulator to switching converter, linear and switching converter in parallel, same converter or same transistor operating either in linear or switching mode
• CPC Class Codes: H02M 3/073 Charge pumps of the Schenkel-type

Abstract

A power management system includes a voltage booster in combination with a voltage regulator to provide a regulated output voltage. The voltage provided to the voltage regulator is used to selectively enable/disable the doubling functionality of the voltage booster to increase power conversion efficiency.

Claims

1. An apparatus for providing a regulated output voltage, comprising:

a voltage regulator that is arranged to provide the regulated output voltage in response to a boost voltage;

a voltage booster that is arranged to selectively distribute charge from a first capacitance circuit to a second capacitance circuit when activated and prevent the distribution of charge from the first capacitance circuit to the second capacitance circuit when deactivated, wherein the boost voltage is associated with the second capacitance circuit such that the boost voltage increases when the voltage booster is activated and decreases when the voltage booster is deactivated;

a boost control that is arranged to selectively control the voltage booster in response to a comparison of the boost voltage and the regulated output voltage such that the voltage booster is deactivated when the boost voltage is above the regulated output voltage by a predetermined level; and

an oscillator that is arranged to provide a control signal to the voltage booster, wherein operation of the oscillator is unaffected by operation of the boost control, the voltage booster, and the voltage regulator.

2. The apparatus of claim 1, further comprising a startup delay that is arranged to prevent the boost control circuit from deactivating the voltage booster during power up.

3. The apparatus of claim 1, wherein the voltage booster is further arranged such that the first capacitance circuit is selectively coupled to the second capacitance circuit in response to the control signal when the voltage booster is activated.

4. The apparatus of claim 1, wherein the voltage booster is deactivated during a first phase and activated during a second phase, wherein the first phase and the second phase are different from one another.

5. The apparatus of claim 4, wherein the first phase is entered when the boost voltage is above the regulated output voltage by a predetermined level, and the second phase is entered when the boost voltage is above the regulated output voltage by another predetermined level.

6. The apparatus of claim 1, wherein the voltage booster is arranged such that:

the first capacitance circuit is selectively coupled between a first voltage supply and a second voltage supply during a first interval when the voltage booster is activated, and the first capacitance circuit is selectively coupled between the first voltage supply and the second capacitance circuit during a second interval when the voltage booster is activated.

7. The apparatus of claim 6, wherein the first capacitance circuit includes a first terminal and second terminal, such that:

the first terminal is coupled to the first voltage supply and the second terminal is coupled to the second voltage supply during the first interval, and the first terminal is coupled to the second capacitance circuit and the second terminal is coupled to the first voltage supply during the second interval.

8. The apparatus of claim 6, wherein the second voltage supply corresponds to ground.

9. The apparatus of claim 1, wherein the voltage booster is arranged such that:

the first capacitance circuit is selectively coupled between a first voltage supply and a second voltage supply during the first interval when the voltage booster is deactivated, and the first capacitance circuit remains selectively coupled between the first voltage supply and the second voltage supply during the second interval when the voltage booster is activated.

10. A method for providing a regulated output voltage, comprising:

charging a first capacitance circuit in a voltage booster to provide a charge during a first interval when the voltage booster is active;

transferring the charge from the first capacitance circuit to a second capacitance circuit in the voltage booster to provide a boost voltage during a second interval when the voltage booster is active;

determining a difference between the boost voltage and the regulated output voltage;

deactivating the voltage booster during a first phase when the difference between the boost voltage and the regulated output voltage is above a first threshold, wherein the boost voltage decreases and the distribution of charge from the first capacitance circuit to the second capacitance circuit is prevented when the voltage booster is deactivated;

activating the voltage booster during a second phase when the difference between the boost voltage and the regulated output voltage is below a second threshold, wherein the boost voltage increases when the voltage booster is activated;

regulating the boost voltage to provide the regulated output voltage; and

producing a control signal that controls transferring the charge from the first capacitance circuit to the second capacitance circuit, wherein production of the control signal is unaffected by determination of the difference between the boost voltage and regulated output voltage, deactivation of the voltage booster, activation of the voltage booster, aid regulation of the boost voltage.

11. The method of claim 10, further comprising selectively coupling the first capacitance circuit between a first voltage supply and a second voltage supply during the first interval when the voltage booster is activated, and selectively coupling the first capacitance circuit between the first voltage supply and the second capacitance circuit during the second interval when the voltage booster is activated.

12. The method of claim 11, further comprising selectively coupling a first terminal associated with the first capacitance circuit to the first voltage supply and selectively coupling a second terminal associated with the first capacitance circuit to the second voltage supply during the first interval.

13. The method of claim 11, further comprising selectively coupling a first terminal associated with the first capacitance circuit to the second capacitance circuit and selectively coupling a second terminal associated with the first capacitance circuit to the first voltage supply during the second interval.

14. The method of claim 10, further comprising selectively coupling the first capacitance circuit between a first voltage supply and a second voltage supply during both the first interval and the second interval when the voltage booster is deactivated.

15. The method of claim 10, wherein the first capacitance circuit is selectively coupled to the second capacitance circuit in response to the control signal when the voltage booster is activated.

16. The method of claim 10, further comprising producing a delay signal, wherein delay signal prevents the voltage booster from deactivating during power up.

17. An apparatus for providing a regulated output voltage, comprising:

means for charging a first capacitance circuit in a voltage booster to provide a charge during a first interval when the voltage booster is active;

means for transferring the charge from the first capacitance circuit to a second capacitance circuit in the voltage booster to provide a boost voltage during a second interval when the voltage booster is active;

means for determining a difference between the boost voltage and the regulated output voltage;

means for deactivating the voltage booster during a first phase when the difference between the boost voltage and the regulated output voltage is above a first threshold, wherein the boost voltage decreases and the distribution of charge from the first capacitance circuit to the second capacitance circuit is prevented when the voltage booster is deactivated;

means for activating the voltage booster during a second phase when the difference between the boost voltage and the regulated output voltage is below a second threshold, wherein the boost voltage increases when the voltage booster is activated;

means for regulating the boost voltage to provide the regulated output voltage; and

means for producing a control signal that controls transferring the charge from the first capacitance circuit to the second capacitance circuit, wherein the means for producing the control signal is unaffected by the means for determination of the difference between the boost voltage and regulated output voltage, the means for deactivating of the voltage booster, the means for activating of the voltage booster, and the means for regulating of the boost voltage.

18. The apparatus of claim 17, further comprising means for selectively coupling the first capacitance circuit between a first voltage supply and a second voltage supply during the first interval when the voltage booster is activated, and means for selectively coupling the first capacitance circuit between the first voltage supply and the second capacitance circuit during the second interval when the voltage booster is activated.

19. The apparatus of claim 17, further comprising means for selectively coupling the first capacitance circuit between a first voltage supply and a second voltage supply during the first phase, wherein charge corresponding to the first capacitance circuit is maintained at a selected level.

20. The apparatus of claim 17, wherein the first capacitance circuit is selectively coupled to the second capacitance circuit in response to the control signal when the voltage booster is activated.