Circuit and method for providing power supply redundancy

• US 6,597,073 B1
• Filed: 02/18/1998
• Issued: 07/22/2003
• Est. Priority Date: 02/18/1998
• Status: Expired due to Fees

• Current Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Original Assignee: Compaq Information Technologies Group LP (HP Inc.)
• Inventors: Check, Ken
• Primary Examiner(s): Sircus, Brian
• Assistant Examiner(s): RIOS CUEVAS, ROBERTO JOSE
• Application Number:
  US09/025,729
• Time in Patent Office: 1,980 Days
• Field of Search: 307/43, 307/44, 307/64, 307/65, 307/66, 307/80, 307/85, 307/86, 307/87, 307/130, 361/66, 361/62, 361/93, 361/100
• US Class Current: 307/64
• CPC Class Codes: G06F 1/30 Means for acting in the event of power-supply failure or interruption, e.g. power-supply fluctuations for resetting only G06F1/24
• CPC Class Codes: G06F 1/305 in the event of power-supply fluctuations
• CPC Class Codes: G06F 11/2015 Redundant power supplies power supply failure G06F1/30

Abstract

The circuit includes a first power supply coupled to power supply sensor, which is in turn coupled to a first switch and to a third switch. A second power supply is coupled to a second power supply sensor, which is in turn coupled to a second switch and a fourth switch. A first disk drive sensor couples the first and second switches to a first disk drive. A second disk drive sensor couples the third and fourth switches to a second disk drive. The first power supply sensor examines the first power supply to recognize when a failure occurs. When the first power supply is functioning, the first power supply sensor drives the first switch to remain closed and drives the third switch to remain open. Accordingly, the first power supply powers the first disk drive. Upon recognition of a failure, the first power supply sensor drives the first switch to open and the second switch to close. The second power supply then powers the first disk drive and the second disk drive clusters. The second power supply sensor examines the second power supply to recognize when a failure occurs. When the second power supply is functioning, the second power supply sensor drives the fourth switch to remain closed and the third switch to open. Accordingly, the second power supply powers the second disk drive. Upon recognition of a failure, the second power supply sensor drives the fourth switch to open and the third switch to close. Thus, the first power supply powers the first disk drive and the second disk drive clusters. The first disk drive sensor examines the first disk drive to recognize if a failure occurs. Upon recognition of a failure, the first disk drive sensor drives the first and second switches to remain open, thereby isolating the first disk drive from the first power supply and the second power supply. The second disk drive sensor examines the second disk drive to recognize if the second disk drive fails. Upon recognition of a failure, the second disk drive sensor drives the third and fourth switches to remain open, thereby isolating the second disk drive from the first and second power supplies.

Claims

1. A circuit comprising:

a first switch for coupling a first power supply to a first load when said first power supply is functioning, the first switch comprising a first transistor coupled to the first power supply and a second transistor coupled to the first transistor and the first load;

a second switch for coupling a second power supply to a second load when said second power supply is functioning, the second switch comprising a third transistor coupled to the second power supply and a fourth transistor coupled to the third transistor and the second load;

a third switch for coupling the second power supply to the first load when the first power supply fails, the third switch comprising a fifth transistor coupled to the second power supply and a sixth transistor coupled to the fifth transistor and the first load;

a fourth switch for coupling the first power supply to the second load when the second power supply fails, the fourth switch comprising a seventh transistor coupled to the first power supply and an eighth transistor coupled to the seventh transistor and the second load;

a voltage sensor coupled to the first power supply, the voltage sensor adapted to detect a malfunction of the first power supply by comparing a voltage between the first power supply and the first switch to a pre-defined static voltage threshold; and

a glitch protector coupled to the first load, to the second transistor, and to the fourth transistor, the glitch protector configured to maintain substantially constant voltage to the first load during the transition of the power supplies.

2. The circuit of claim 1, wherein the first switch isolates the first power supply from the first load when the first power supply fails.

3. The circuit of claim 1 wherein the detector further comprises a comparator for comparing the first power supply against a reference voltage to determine whether the first power supply is functioning.

4. The circuit of claim 3, wherein the comparator controls the first switch.

5. The circuit of claim 3, wherein the comparator controls the third switch.

6. The circuit of claim 1 wherein the detector further comprises a comparator for comparing the second power supply against a reference voltage to determine whether the second power supply is functioning.

7. The circuit of claim 6, wherein the comparator controls the second switch.

8. The circuit of claim 6, wherein the comparator controls the fourth switch.

9. The circuit of claim 3, further comprising a lockout timer coupled to the first comparator for maintaining the results of the comparison for a predetermined time.

10. The circuit of claim 1, further comprising threshold sensing logic coupled to the first power supply for determining whether the first power supply provides a voltage that is greater than a predetermined voltage.

11. The circuit of claim 1, further comprising a first direct current power supply operatively coupled to the first switch.

12. The circuit of claim 11, further comprising a second direct current power supply operatively coupled to the second switch.

13. The circuit of claim 12, wherein the switches are configured to switch a direct current.

14. The circuit of claim 1 further comprising:

a first load sensor coupled to the first load and second transistor and configured to permit the first switch to disconnect the first load from the first power supply and to permit the third switch to disconnect the first load from the second power supply when the first load fails.

15. The circuit of claim 1 further comprising:

a second load sensor coupled to the second load and fourth transistor and configured to permit the second switch to disconnect the second load from the second power supply and to permit the fourth switch to disconnect the second load from the first power supply when the second load fails.

16. The circuit of claim 1 further comprising:

a second voltage sensor coupled to the second power supply, the second voltage sensor adapted to detect a malfunction of the second power supply by comparing a voltage between the second power supply and the second switch to a pre-defined static voltage threshold.

17. A method comprising:

coupling a first power supply to a first load when said first power supply is functioning, the coupling the first power supply to the first load step further comprising turning on a first transistor coupled to the first power supply and a second transistor coupled to the first transistor and to the first load to permit current to conduct from the first power supply to the first load;

coupling a second power supply to a second load when said second power supply is functioning, the coupling the second power supply to the second load step further comprising turning on a third transistor coupled to the second power supply and a fourth transistor coupled to the third transistor and to the second load to permit current to conduct from the second power supply to the second load;

sensing a voltage between the first power supply and the first switch and comparing the voltage to a pre-defined static voltage in order to determine whether the first power supply is failing;

coupling the second power supply to the first load when the first power supply fails, the coupling the second power supply to the first load step further comprising turning on a fifth transistor coupled to the second power supply and a sixth transistor coupled to the fifth transistor and to the first load to permit current to conduct from the second power supply to the first load; and

maintaining substantially constant voltage to the load corresponding to the failed power supply during the transition of the power supplies.

18. The method of claim 17, further comprising the step of isolating the first power supply from the first load when the first power supply fails.

19. The method of claim 17, further comprising the step of comparing the first power supply against a pre-defined static voltage to determine whether the first power supply is functioning.

20. The method of claim 19, further comprising the step of maintaining the results of the comparison for a predetermined time.

21. The method of claim 17, wherein the step of coupling a first power supply comprises coupling a first direct current power supply.

22. The method of claim 17, wherein the step of coupling a second power supply comprises coupling a second direct current power supply.

23. A system comprising:

means for coupling a first power supply to a first load when said first power supply is functioning;

means for coupling a second power supply to a second load when said second power supply is functioning;

means for coupling the second power supply to the first load when the first power supply fails;

means for directly sensing a voltage of the second power supply to determine whether the second power supply is failing by comparing the voltage on the second power supply to a pre-defined static voltage threshold;

means for coupling the first power supply to the second load when the second power supply fails;

means for maintaining substantially constant voltage to the load corresponding to the failed power supply during the transition of the power supplies.

24. The system of claim 23, wherein the means for coupling the first power supply to the first load comprises means for coupling a first direct current power supply to the first load.

25. The system of claim 23, wherein the means for coupling the second power supply to the second load includes means for coupling a second direct current power supply to the second load.