SENSING CURRENT TO PROTECT A FUSE

• US 20140089698A1
• Filed: 09/26/2012
• Published: 03/27/2014
• Est. Priority Date: 09/26/2012
• Status: Active Grant

• Current Assignee: Hewlett Packard Enterprise Development LP (Hewlett-Packard Enterprise Company)
• Original Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Inventors: Ng, Kah Hoe, Thoon, Koh Yew, Ng, Kay Seah
• Granted Patent: US 9,223,378 B2
• Time in Patent Office: Days
• US Class Current: 713/322
• CPC Class Codes: G06F 1/3206 Monitoring of events, devices or parameters that trigger a change in power modality
• CPC Class Codes: G06F 1/324 by lowering clock frequency
• CPC Class Codes: Y02D 10/00 Energy efficient computing, e.g. low power processors, power management or thermal management

Abstract

The speed of a processor is adjusted based on the current sensed by a current sensor in order to protect a fuse from being damaged.

Claims

1. A computing device comprising a chassis having a power supply, at least one blade received by the chassis and a fuse between the at least one blade and the power supply;

the at least one blade having a processor, a current sensor to detect the current drawn by the blade and logic circuitry to send a signal to the processor to reduce its operating frequency if the current detected by the current sensor exceeds a current threshold, said current threshold being a threshold above which the fuse may be damaged.

2. The computing device of claim 1 wherein the fuse has a current rating and the current threshold is a selected value in the range 65-105% of the current rating of the fuse.

3. The computing device of claim 1 wherein the current threshold is a selected value equal to L plus or minus 5%, where L=current rating of fuse*[1−

D1−

D2], where D1 is a de-rating factor for the fuse and D2 is a temperature de-rating factor for the fuse.

4. The computing device of claim 1 wherein the signal is a prochot signal.

5. The computing device of claim 1 wherein the logic circuitry is to send a signal to the processor to cause the processor to reduce its operating frequency to the minimum operating frequency when the current sensed by the current sensor exceeds said current threshold.

6. The computing device of claim 1 wherein there are a plurality of processor operating frequencies each with an associated power consumption, and wherein the logic circuitry has a plurality of current thresholds and is to dynamically decrease the operating frequency of the processor each time the current sensed by the current sensor exceeds one of said current thresholds and to increase the operating frequency of the processor each time the current sensed by the current sensor goes below one of said current thresholds.

7. A computing device comprising a chassis having a power supply, at least one blade received by the chassis and a fuse between the at least one blade and the power supply;

the at least one blade comprising;

a CPU;

a current sensor to sense the current drawn by the blade; and

logic circuitry to dynamically adjust the running power of the CPU by adjusting its operating frequency based on the current sensed by the current sensor so that the total power drawn by the blade does not exceed a power threshold above which the fuse may be damaged, said power threshold being based on a current rating of the fuse.

8. The blade of claim 7 wherein said power threshold is determined according to the equation:

P_B=V_B*X*I_F

Where P_B is the power threshold, X is a value selected from the range 0.65 to 1.05,

I_F is the current rating of the fuse and V_B is the operating voltage of the blade.

9. The blade of claim 8 wherein X is a value selected from the range 0.70 to 1.

10. The blade of claim 7 wherein the blade has network routing or switching functionality and comprises a switching chip, a routing table and a plurality of network communication ports.

11. The blade of claim 7 wherein the logic circuitry is to cause the CPU to run at a lower frequency by sending a signal to pin of the CPU.

12. The blade of claim 11 wherein the signal is a prochot signal.

13. The blade of claim 11 wherein the signal is to cause the CPU to operate at its minimum operating frequency.

14. The blade of claim 11 wherein the signal is to cause the CPU to operate at one of a plurality of operating frequencies depending on the current sensed by the current sensor, said plurality of operating frequencies comprising a minimum frequency, a maximum frequency and at least one other frequency.

15. A method of protecting a fuse comprising:

causing a CPU to run at a lower speed in response to sensing that the current drawn by the CPU exceeds a current threshold above which the fuse may be damaged.

16. The method of claim 15 wherein the current threshold is 65-105% of a current rating of the fuse.

17. The method of claim 15 wherein the CPU is caused to run at a lower speed by use of a prochot signal.

18. The method of claim 15 wherein the CPU is located on a blade which is connected to a power supply of a chassis, wherein the fuse is located in the chassis between the power supply and the blade, and wherein the current drawn by the blade is sensed.

19. The method of claim 18 wherein the blade comprises a plurality of power drawing components other than the CPU and the total power drawn by the blade is equal to the sum of the power drawn by the CPU and the plurality of other power drawing components.

20. The method of claim 19 wherein CPU is capable of operating at a plurality of possible speeds including a maximum speed, a minimum speed and at least one other speed, and wherein the method comprises determining the highest speed at which the CPU can safely operate without causing the total power drawn by the blade to exceed a power threshold at which a total current drawn by the blade will damage the fuse.