Granted Patent B1

US 7,330,019 · App. 11/590,704 · Granted Feb 12, 2008

Abstract

Claims (75)

1. A discontinuous switching voltage regulator comprising:

(a) a charging element operable to generate an output voltage;

(b) switching circuitry coupled to the charging element; and

(c) switch control circuitry operable to control the switching circuitry to configure the charging element during a cycle, including to charge the charging element for an on-time, discharge the charging element for a discharge time, and tristate the charging element for a tristate time, and further operable to:

initialize the on-time to a first on-time;

measure a first switch time comprising the first on-time and a first discharge time of a first cycle;

measure a first tristate time of the first cycle;

determine a first ratio of the first tristate time to the first switch time;

compare the first ratio to a first ratio threshold; and

adjust the on-time to a second on-time if the first ratio exceeds the first ratio threshold.

2. The discontinuous switching voltage regulator as recited in claim 1 , wherein the first cycle is started in response to an error signal.

3. The discontinuous switching voltage regulator as recited in claim 2 , wherein the error signal comprises a difference between the output voltage and a reference voltage.

4. The discontinuous switching voltage regulator as recited in claim 2 , wherein:

the error signal comprises a difference between a propagation oscillation signal and a reference oscillation signal; and

the propagation oscillation signal represents a propagation delay of a digital circuit.

5. The discontinuous switching voltage regulator as recited in claim 2 , wherein when the error signal crosses an error threshold, the switching circuitry is configured to begin charging the charging element for the on-time.

6. The discontinuous switching voltage regulator as recited in claim 1 , wherein the charging element comprises an inductor.

7. The discontinuous switching voltage regulator as recited in claim 1 , wherein after the on time, the switching circuitry is configured to discharge the charging element for the discharge time.

8. The discontinuous switching voltage regulator as recited in claim 7 , wherein after the discharge time, the switching circuitry is configured to tristate the charging element for the tristate time.

9. The discontinuous switching voltage regulator as recited in claim 1 , wherein if the first ratio is greater than the first ratio threshold, the second on-time is less than the first on-time.

10. The discontinuous switching voltage regulator as recited in claim 1 , wherein if the first ratio is less than the first ratio threshold, the second on-time is greater than the first on-time.

11. The discontinuous switching voltage regulator as recited in claim 1 , wherein the switch control circuitry is further operable to:

measure a second switch time comprising the second on-time and a second discharge time of a second cycle;

measure a second tristate time of the second cycle;

determine a second ratio of the second tristate time to the second switch time;

compare the second ratio to a second ratio threshold; and

decrease the on-time to a third on-time if the second ratio is greater than the second ratio threshold.

12. The discontinuous switching voltage regulator as recited in claim 11 , wherein:

the second on-time is approximately 1/N times the first on-time; and

the third on-time is approximately 1/N times the second on-time.

13. The discontinuous switching voltage regulator as recited in claim 11 , wherein the switch control circuitry is further operable to:

measure a third switch time comprising the third on-time and a third discharge time of a third cycle;

measure a third tristate time of the third cycle;

determine a third ratio of the third tristate time to the third switch time;

compare the third ratio to a third ratio threshold; and

reset the on-time to the first on-time if the third ratio is less than the third ratio threshold.

14. The discontinuous switching voltage regulator as recited in claim 1 , wherein the switch control circuitry comprises a digital timer for timing the on-time.

15. The discontinuous switching voltage regulator as recited in claim 1 , wherein the switch control circuitry comprises a digital timer for timing the discharge time.

16. The discontinuous switching voltage regulator as recited in claim 1 , wherein the switch control circuitry comprises a digital timer for timing the tristate time.

17. A method of operating a discontinuous switching voltage regulator, the discontinuous switching voltage regulator comprising a charging element operable to generate an output voltage, and switching circuitry coupled to the charging element, wherein the switching circuitry is configured during a cycle, including to charge the charging element for an on-time, discharge the charging element for a discharge time, and tristate the charging element for a tristate time, the method comprising:

initializing the on-time to a first on-time;

measuring a first switch time comprising the first on-time and a first discharge time of a first cycle;

measuring a first tristate time of the first cycle;

determining a first ratio of the first tristate time to the first switch time;

comparing the first ratio to a first ratio threshold; and

adjusting the on-time to a second on-time if the first ratio exceeds the first ratio threshold.

18. The method as recited in claim 17 , wherein the first cycle is started in response to an error signal.

19. The method as recited in claim 18 , wherein the error signal comprises a difference between the output voltage and a reference voltage.

20. The method as recited in claim 18 , wherein:

the error signal comprises a difference between a propagation oscillation signal and a reference oscillation signal; and

the propagation oscillation signal represents a propagation delay of a digital circuit.

21. The method as recited in claim 18 , wherein when the error signal crosses an error threshold, the switching circuitry is configured to charge the charging element for the on-time.

22. The method as recited in claim 17 , wherein the charging element comprises an inductor.

23. The method as recited in claim 17 , wherein after the on time, the switching circuitry is configured to discharge the charging element for the discharge time.

24. The method as recited in claim 23 , wherein after the discharge time, the switching circuitry is configured to tristate the charging element for the tristate time.

25. The method as recited in claim 17 , wherein if the first ratio is greater than the first ratio threshold, the second on-time is less than the first on-time.

26. The method as recited in claim 17 , wherein if the first ratio is less than the first ratio threshold, the second on-time is greater than the first on-time.

27. The method as recited in claim 17 , further comprising:

measuring a second switch time comprising the second on-time and a second discharge time of a second cycle;

measuring a second tristate time of the second cycle;

determining a second ratio of the second tristate time to the second switch time;

comparing the second ratio to a second ratio threshold; and

decreasing the on-time to a third on-time if the second ratio is greater than the second ratio threshold.

28. The method as recited in claim 27 , wherein:

the second on-time is approximately 1/N times the first on-time; and

the third on-time is approximately 1/N times the second on-time.

29. The method as recited in claim 27 , further comprising:

measuring a third switch time comprising the third on-time and a third discharge time of a third cycle;

measuring a third tristate time of the third cycle;

determining a third ratio of the third tristate time to the third switch time;

comparing the third ratio to a third ratio threshold; and

resetting the on-time to the first on-time if the third ratio is less than the third ratio threshold.

30. The method as recited in claim 17 , wherein a digital timer is used to time the on-time.

31. The method as recited in claim 17 , wherein a digital timer is used to time the discharge time.

32. The method as recited in claim 17 , wherein a digital timer is used to time the tristate time.

Assignments (8)