Method and apparatus for fault condition protection of a switched mode power supply

• US 6,580,593 B2
• Filed: 03/08/2002
• Issued: 06/17/2003
• Est. Priority Date: 03/14/2001
• Status: Active Grant

• Current Assignee: Power Integrations Incorporated
• Original Assignee: Power Integrations Incorporated
• Inventors: Balakrishnan, Balu
• Primary Examiner(s): Riley, Shawn
• Application Number:
  US10/092,601
• Publication Number:
  US 20020131280A1
• Time in Patent Office: 466 Days
• Field of Search: 361/18, 361/94, 361/95, 361/96, 361/97, 361/90, 361/91.1, 361/89, 361/93.9
• US Class Current: 361/97
• CPC Class Codes: H02H 3/06 with automatic reconnection
• CPC Class Codes: H02H 3/087 for dc applications
• CPC Class Codes: H02M 1/32 Means for protecting converters other than automatic disconnection
• CPC Class Codes: H02M 1/36 Means for starting or stopping converters

Abstract

Methods and apparatuses for fault condition protection of a switched mode power supply. In one aspect of the invention, a power supply circuit having an auto-restart function to turn the power supply on and off repeatedly under fault conditions is included. In one embodiment, one or more off-times following detection of a fault condition is smaller than subsequent off-times.

Claims

1. A power supply circuit, comprising:

a first terminal to be coupled to an energy transfer element having an energy transfer element input and output, the energy transfer element input coupled to a first terminal of a power supply input;

a second terminal to be coupled to a second terminal of the power supply input;

a third terminal to be coupled to receive at least feedback information of a power supply output;

a control circuitry coupled to the first, second and third terminals, the control circuitry to control power delivered to the power supply output from the power supply input in response to said at least feedback information of the power supply output; and

an auto-restart circuit coupled to the third terminal and the control circuitry, the auto-restart circuit coupled to the control circuitry to repeatedly enable and disable the power supply during a fault condition, wherein a duration of at least one disable period following a detection of a fault condition of the power supply is smaller than durations of subsequent disable periods.

2. The power supply circuit of claim 1 wherein the fault condition is an open loop condition.

3. The power supply circuit of claim 2 wherein the open loop condition is a result of at least one of a power supply output short circuit condition and a power supply overload condition.

4. The power supply circuit of claim 3 wherein the power supply overload condition is caused by a power supply input under-voltage condition.

5. The power supply circuit of claim 1 wherein the control circuitry comprises a power switch coupled between the first and second terminals, the power switch switched in response to a switching signal to control the power delivered to the power supply output from the power supply input.

6. The power supply circuit of claim 1 wherein a duration of a first disable period following the detection of the fault condition of the power supply is smaller than durations of subsequent disable periods.

7. The power supply circuit of claim 1 wherein said at least one disable period following the detection of the fault condition of the power supply is a fixed number.

8. The power supply circuit of claim 1 wherein the detection of the fault condition of the power supply occurs after the power supply has been in regulation.

9. The power supply circuit of claim 8 wherein said at least one disable period following the detection of the fault condition of the power supply is a fixed number.

10. A power supply, comprising:

an energy transfer element having an energy transfer element input and an energy transfer element output, the energy transfer element input coupled to a first terminal of an input of the power supply, the energy transfer element output coupled to an output of the power supply;

a power supply controller including a power switch coupled between the energy transfer element input and a second terminal of the input of the power supply, the power supply controller further coupled to the energy transfer element output, a feedback signal generated in response to the energy transfer element output, the power switch switched to modulate power delivered to the output of the power supply from the input of the power supply in response to the feedback signal; and

an auto restart circuit included in the power supply controller coupled to repeatedly enable and disable the power supply during a power supply fault condition, wherein a fixed number of disable periods following a detection of the power supply fault condition after the power supply has been in regulation have smaller durations than durations of subsequent disable periods.

11. The power supply of claim 10 wherein the power supply fault condition is an open loop condition.

12. The power supply of claim 11 wherein the open loop condition is a result of at least one of a power supply output short circuit condition and a power supply overload condition.

13. The power supply of claim 12 wherein the power supply overload condition is caused by a power supply input under-voltage condition.

14. The power supply of claim 11 wherein the open loop condition is detected by the power supply controller in response to the feedback signal being idle for a predetermined period of time.

15. The power supply of claim 14 the feedback signal is a digital signal with two states.

16. The power supply of claim 15 wherein the feedback signal being idle for the predetermined period of time occurs when the feedback signal is in one of the two states for the predetermined period of time.

17. The power supply of claim 10 wherein the power supply is a switched mode power supply.

18. The power supply of claim 10 wherein the power supply controller further coupled to receive the feedback signal from energy transfer element input to further detect a power supply input under-voltage condition.

19. The power supply of claim 10 wherein only a duration of a first disable period following the detection of the power supply fault condition has a smaller duration than the durations of the subsequent disable periods.

20. A method, comprising:

regulating a delivery of power from a power supply input to a power supply output;

detecting a fault condition in the power supply; and

repeatedly enabling and disabling the power supply during the fault condition until the fault condition is no longer present in the power supply, wherein a duration of one or more disable periods follow the detection of the fault condition in the power supply is smaller than a duration of subsequent disable periods.

21. The method of claim 20 wherein detecting the fault condition in the power supply includes detecting an open loop condition in the power supply.

22. The method of claim 21 wherein detecting the open loop condition in the power supply includes detecting at least one of a power supply output short circuit condition and a power supply output overload condition in the power supply.

23. The method of claim 22 wherein the power supply output overload condition is caused by a power supply input under-voltage condition in the power supply.

24. The method of claim 20 wherein regulating the delivery of power from the power supply input to the power supply output includes switching a power switch in response to a switching signal, the power switch to switchably couple an energy transfer element of the power supply to the power supply input.

25. The method of claim 20 wherein only a duration of a first disable period following the detection of the fault condition in the power supply is smaller than the duration of subsequent disable periods.

26. The power supply circuit of claim 20 wherein the detection of the fault condition in the power supply occurs after the power supply has been in regulation.