Method and apparatus for powering up an electronic system after AC power has been removed

• US 6,504,266 B1
• Filed: 01/18/2000
• Issued: 01/07/2003
• Est. Priority Date: 01/18/2000
• Status: Expired due to Term

• Current Assignee: Oracle America, Inc. (Oracle Corporation)
• Original Assignee: Sun Microsystems Incorporated (Oracle Corporation)
• Inventors: Ervin, Joseph J.
• Primary Examiner(s): Sircus, Brian
• Assistant Examiner(s): RIOS CUEVAS, ROBERTO JOSE
• Application Number:
  US09/484,093
• Time in Patent Office: 1,085 Days
• Field of Search: 307/18, 307/19, 307/29, 307/126, 713/300, 713/340, 361/93.7, 361/18, 700/286, 700/291, 700/293, 700/295, 702/57, 702/58, 702/64
• US Class Current: 307/29
• CPC Class Codes: G06F 1/263 Arrangements for using multiple switchable power supplies, e.g. battery and AC G06F1/30 takes precedence
• CPC Class Codes: G06F 1/28 Supervision thereof, e.g. detecting power-supply failure by out of limits supervision
• CPC Class Codes: H02J 1/10 Parallel operation of dc sources

Abstract

In an electronic system with multiple power supplies, a method and apparatus dynamically determines the number of power supplies required to power up the system without overloading any supply. The individual power supplies do not turn on until the determined number of power supplies have received AC power and become operational before attempting a complete system power on. The amount of required power is determined before power up based on the actual power load present. The actual load is determined by sensing load indicators in each load device and computing the total power load. The amount of power from supplies which have received AC power is determined by detecting when AC power has been applied to each power supply and computing the total amount of power available. System power up is delayed when the number of power supplies which have received AC power is insufficient to power the system without an overload situation occurring.

Claims

1. Apparatus for powering up an electronic system after AC power-has been removed, the electronic system having a plurality of independent power supplies and a plurality of load devices and the apparatus comprising:

a load calculator which is operable before AC power has been applied to the electronic system and detects the power load of each of the plurality of load devices and computes the total power load;

a power available calculator which is operable before AC power has been applied to the electronic system and detects when AC power has been applied to each power supply and computes the total available power; and

a power control circuit which delays system power up when the total available power is insufficient to power the total power load without an overload situation occurring in any power supply.

2. Apparatus according to claim 1 wherein the load calculator uses a load indicator in each load device to determine the power load of the load device.

3. Apparatus according to claim 2 wherein the load indicator is a resistor with a value selected to represent the power load of the load device.

4. Apparatus according to claim 1 wherein the power available calculator uses a power supply indicator in each power supply to determine when the supply is energized with AC power.

5. Apparatus according to claim 4 wherein the power supply indicator indicates the amount of power the supply can provide.

6. Apparatus according to claim 4 wherein the power supply indicator is a resistor with a value selected to represent the amount of power the supply can provide.

7. Apparatus according to claim 6 wherein the resistor is connected to a standby power source in the supply which is activated when AC power is applied to the supply.

8. Apparatus according to claim 1 wherein the available supply power of each of the plurality of power supplies is represented by a current whose value is related to the available supply power.

9. Apparatus according to claim 8 wherein the available supply power of each of the plurality of power supplies is represented by a current whose value is proportional to the available supply power.

10. Apparatus according to claim 8 wherein the power available calculator computes the total available supply power by adding currents representing the power available from each power supply.

11. Apparatus according to claim 1 wherein the power load of each of the plurality of load devices is represented by a current whose value is related to the power load.

12. Apparatus according to claim 11 wherein the power load of each of the plurality of load devices is represented by a current whose value is proportional to the power load.

13. Apparatus according to claim 11 wherein the load calculator computes the total power load by adding currents representing each load device.

14. Apparatus according to claim 1 wherein the power control circuit comprises a comparator which compares the total available power to the total power load.

15. Apparatus according to claim 14 wherein the comparator generates an overload signal when the total power load exceeds the total available power.

16. Apparatus according to claim 15 wherein the power control circuit further comprises an asynchronous state machine which turns the power supplies on when system power is requested and the overload signal indicates that the total available power is equal or greater than the total power load and which prevents the apparatus from turning off the power supplies in response to an overload signal after the power supplies have been turned on.

17. A method for powering up an electronic system after AC power-has been removed, the electronic system having a plurality of independent power supplies and a plurality of load devices and the method comprising:

(a) before AC power is applied to the electronic system, detecting the power load of each of the plurality of load devices and computing the total power load;

(b) before AC power is applied to the electronic system, detecting when AC power has been applied to each power supply and computing the total available power; and

(c) delaying system power up when the total available power is insufficient to power the total power load without an overload situation occurring in any power supply.

18. A method according to claim 17 wherein step (a) comprises:

(a1) using a load indicator in each load device to determine the power load of the load device.

19. A method according to claim 18 wherein step (a1) comprises using a resistor with a value selected to represent the power load of the load device.

20. A method according to claim 17 wherein step (b) comprises:

(b1) using a power supply indicator in each power supply to determine when the supply is energized with AC power.

21. A method according to claim 20 wherein step (b1) comprises using the power supply indicator to indicate the amount of power the supply can provide.

22. A method according to claim 20 wherein step (b1) comprises using a resistor with a value selected to represent the amount of power the supply can provide.

23. A method according to claim 22 wherein step (b1) further comprises connecting the resistor to a standby power source in the supply which is activated when AC power is applied to the supply.

24. A method according to claim 17 wherein step (b) comprises:

(b2) representing the available supply power of each of the plurality of power supplies by a current whose value is related to the available supply power.

25. A method according to claim 24 wherein step (b2) comprises:

(b2a) representing the available supply power of each of the plurality of power supplies by a current whose value is proportional to the available supply power.

26. A method according to claim 24 wherein step (b) further comprises computing the total available supply power by adding currents representing the power available from each power supply.

27. A method according to claim 17 wherein step (a) comprises representing the power load of each of the plurality of load devices by a current whose value is related to the power load.

28. A method according to claim 27 wherein step (a) comprises representing the power load of each of the plurality of load devices by a current whose value is proportional to the power load.

29. A method according to claim 27 wherein the step (a) further comprises computing the total power load by adding currents representing each load device.

30. A method according to claim 17 wherein step (c) comprises comparing the total available power to the total power load.

31. A method according to claim 30 wherein step (c) further comprises generating an overload signal when the total power load exceeds the total available power.

32. A method according to claim 31 wherein step (c) further comprises using an asynchronous state machine to turn the power supplies on when system power is requested and the overload signal indicates that the total available power is equal or greater than the total power load and which to prevent the apparatus from turning off the power supplies in response to an overload signal after the power supplies have been turned on.