Independently controlling passive and active cooling in a computer system

• US 6,470,289 B1
• Filed: 08/05/1999
• Issued: 10/22/2002
• Est. Priority Date: 08/05/1999
• 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: Peters, Mark W., Hodge, Richard H.
• Primary Examiner(s): Hoff, Marc S.
• Assistant Examiner(s): Raymond, Edward
• Application Number:
  US09/368,950
• Time in Patent Office: 1,174 Days
• Field of Search: 702/130, 702/131, 702/132, 702/133, 702/99, 374/10, 374/11, 374/100, 374/103, 374/112, 374/113, 374/114, 374/120, 374/145, 374/163, 361/158, 713/300
• US Class Current: 702/132
• CPC Class Codes: G01K 7/42 Circuits effecting compensation of thermal inertia; Circuits for predicting the stationary value of a temperature
• CPC Class Codes: G06F 1/206 comprising thermal management
• CPC Class Codes: Y02D 10/00 Energy efficient computing, e.g. low power processors, power management or thermal management

Abstract

A computer system having thermal control logic that efficiently cools the computer system. In accordance with one embodiment of the invention, the thermal control logic couples to a CPU module and a fan. The CPU module includes a pair of temperature response elements. One temperature response element located near or on the CPU core logic or die on which the CPU is fabricated. The other temperature response element is located near or on an exterior surface of the CPU module. The thermal control logic monitors the temperature of recorded by each temperature response element and controls the speed of the fan and the frequency of the CPU core clock independently. Preferably, the thermal control logic adjusts the fan speed as a function of the temperature recorded by the temperature element adjacent an exterior surface of the CPU module. The thermal control logic also adjusts the frequency of the CPU clock signal as a function of the temperature recorded by the temperature response element adjacent the CPU core. By disassociating control of the fan speed from the temperature of the CPU core, the annoyance in conventional computer systems caused fans that rapidly turn on and off or change speed rapidly is reduced.

Claims

1. A computer system, comprising:

a CPU, wherein said CPU further comprises;

a CPU core;

clock control logic coupled to said CPU core and providing a periodic clock signal to said CPU core;

at least two temperature response elements within said CPU;

wherein a first temperature response element is adjacent to said CPU core;

a temperature sensor coupled to said first temperature response element, said temperature sensor including a second temperature response element, and said temperature sensor capable of monitoring the temperature of said first and second temperature response elements; and

thermal control logic coupled to said temperature sensor and said clock control logic;

a fan coupled to said thermal control logic;

wherein said temperature sensor provides a value indicative of the temperature of said first and second temperature response elements to said thermal control logic and said thermal control logic independently controls the frequency of the clock signal provided to said CPU core and the speed of said fan based on the temperatures of the first and second temperature response elements.

2. The computer system of claim 1 wherein said CPU core, clock control logic, first and second temperature response elements, and said temperature sensor are included in a single monolithic package.

3. The computer system of claim 1 wherein said temperature sensor includes at least one temperature register in which temperature values indicative of the first and second temperature response elements are stored.

4. The computer system of claim 3 wherein said thermal control logic includes a controller that reads the temperature values from the temperature register.

5. The computer system of claim 4 wherein said computer system also includes a keyboard and said controller is a keyboard controller coupled to said keyboard and receives signals from said keyboard.

6. The computer system of claim 4 further including a fan controller coupled between said controller and said fan and said controller provides a signal to the fan controller indicative of the desired speed of the fan.

7. The computer system of claim 6 wherein the signal indicative of the desired fan speed is a pulse width modulated signal.

8. The computer system of claim 6 wherein said CPU core provides temperature threshold values to said controller, said temperature threshold values define at least one temperature range.

9. The computer system of claim 8 further including main memory coupled to the CPU core in which first and second temperature control tables are stored, each of said tables defining an operating characteristic of the computer system as a function of temperature.

12. The computer system of claim 6 further including a bridge device coupled between said CPU core and said controller.

18. The computer system of claim 1 wherein the thermal control logic adjusts the frequency of the clock signal before adjusting the speed of said fan.

10. A computer system, comprising:

a CPU core;

clock control logic coupled to said CPU and providing a periodic clock signal to said CPU;

a first temperature response element adjacent to said CPU core;

a temperature sensor coupled to said first temperature response element, said temperature sensor including a second temperature response element, and said temperature sensor capable of monitoring the temperature of said first and second temperature response elements;

thermal control logic coupled to said temperature sensor and said clock control logic;

a fan coupled to said thermal control logic;

wherein said temperature sensor provides a value indicative of the temperature of said first and second temperature response elements to said thermal control logic and said thermal control logic independently controls the frequency of the clock signal provided to said CPU core and the speed of said fan based on the temperatures of the first and second temperature response elements;

wherein said temperature sensor includes at least one temperature register in which temperature values indicative of the first and second temperature response elements are stored;

wherein said thermal control logic includes a controller that reads the temperature values from the temperature register;

a fan controller coupled between said controller and said fan and said controller provides a signal to the fan controller indicative of the desired speed of the fan;

wherein said CPU core provides temperature threshold values to said controller, said temperature threshold values define at least one temperature range; and

main memory coupled to the CPU core in which first and second temperature control tables are stored, each of said tables defining an operating characteristic of the computer system as a function of temperature;

wherein the first temperature control table specifies the level of CPU throttling in relation to the temperature of the first temperature response element.

11. The computer system of claim 10 wherein the second temperature control table specifies the desired fan speed in relation to the temperature of the second temperature response element.

13. The computer system of claim 11 wherein said controller also connects to the CPU via a system management bus and reads the current temperatures of each of the first and second temperature response elements from the temperature register.

14. The computer system of claim 13 wherein said controller asserts a first interrupt signal to the bridge device if one of the current temperatures of each of the first and second temperature response elements exceeds its associated temperature range.

15. The computer system of claim 14 wherein the bridge device responds to the asserted first interrupt signal by asserting a second interrupt signal to the CPU core which responds by determining which temperature response element caused the controller to assert the first interrupt signal and by determining the current temperature of the temperature response element that caused the first interrupt to be asserted.

16. The computer system of claim 15 wherein the CPU core compares the current temperature to the first temperature control table if the first temperature response element caused the controller to assert the first interrupt signal.

17. The computer system of claim 15 wherein the CPU core compares the current temperature to the second temperature control table if the second temperature response element caused the controller to assert the first interrupt signal.

19. A computer system, comprising:

a CPU core;

clock control logic coupled to said CPU and providing a periodic clock signal to said CPU;

a first temperature response element adjacent to said CPU core;

a temperature sensor coupled to said first temperature response element, said temperature sensor including a second temperature response element, and said temperature sensor capable of monitoring the temperature of said first and second temperature response elements;

thermal control logic coupled to said temperature sensor and said clock control logic; and

a fan coupled to said thermal control logic;

wherein said temperature sensor provides a value indicative of the temperature of said first and second temperature response elements to said thermal control logic and said thermal control logic independently controls the frequency of the clock signal provided to said CPU core and the speed of said fan based on the temperatures of the first and second temperature response elements; and

wherein said thermal control logic includes hysteresis in controlling the fan speed.

20. A method for controlling the temperature of a computer system, comprising:

(a) monitoring the temperatures at two locations within a CPU;

(b) comparing the temperatures at the two locations to predetermined temperature ranges, each temperature range associated with the temperature at one of said two locations;

(c) independently controlling the speed of a fan or the frequency of a CPU clock signal based on the temperatures at the two locations.

21. The method of claim 20 wherein the locations of step (a) include a CPU die and an area in an outer region of the CPU.

22. The method of claim 21 wherein step (c) includes adjusting the fan speed if the temperature of the area in the outer CPU region exceeds an associated predetermined temperature range.

23. The method of claim 22 wherein step (c) includes adjusting the CPU clock signal frequency if the temperature of the CPU die exceeds an associated predetermined temperature range.

24. The method of claim 21 wherein step (c) includes adjusting the frequency of the CPU clock frequency before adjusting the speed of the fan.

25. The method of claim 20 further including asserting an interrupt signal if the temperature of either location exceeds an associated temperature range.

26. A method for controlling the temperature of a computer system, comprising:

monitoring the temperatures at two locations within a CPU;

comparing the temperatures at the two locations to predetermined temperature ranges, each temperature range associated with the temperature at one of said two locations;

independently controlling the speed of a fan or the frequency of a CPU clock signal based on the temperatures at the two locations;

wherein the two locations include a CPU die and an area in an outer region of the CPU; and

storing first and second control tables in memory, the first control table used to control fan speed as a function of the temperature of the outer region of the CPU and the second control used to control CPU clock signal frequency as a function of the temperature of the CPU die.

27. The method of claim 26 wherein the first control table includes a first plurality of temperature ranges for the outer region of the CPU and a fan speed setting associated with each of the first plurality of temperature ranges.

28. The method of claim 27 further including comparing the current temperature of the outer region to the first plurality of temperature ranges.

29. The method of claim 26 wherein the second control table includes a second plurality of temperature ranges for the CPU die and a setting for CPU clock signal frequency associated with each of the second plurality of temperature ranges.

30. The method of claim 29 further including comparing the current temperature of the CPU die to the second plurality of temperature ranges.

31. A thermal control system for a computer, comprising:

a CPU including;

a CPU core fabricated on a semiconductor die packaged within said CPU;

a temperature sensor located in an exterior region of said CPU;

a first temperature response element thermally coupled to the semiconductor die and coupled to said temperature sensor; and

a second temperature response included as part of the temperature sensor;

wherein said temperature sensor monitors the temperatures detected by the first and second temperature response elements and stores temperature values indicative of the detected temperatures in at least one register;

a clock control logic coupled to said CPU core and providing a periodic CPU clock signal to said CPU core, the frequency of the CPU clock signal being adjustable;

a controller coupled to said CPU via a first bus, said CPU provides the temperature values from said at least one register to said controller via said first bus and said controller compares the temperature values to predetermined temperature ranges and generates a first interrupt signal if one of the temperature ranges is exceeded; and

a fan coupled to said controller.

32. The thermal control system of claim 31 wherein said controller is a keyboard controller that receives input signals from a keyboard.

33. The thermal control system of claim 31 wherein said first interrupt signal is provided to a first bridge device coupled between said controller and said CPU, and said first bridge device responds to the first interrupt signal by asserting a second interrupt signal to the CPU.

34. The thermal control system of claim 33 further including a second bridge device coupled between the first bridge device and the CPU and also coupled to main memory, and said CPU responds to said second interrupt signal by receiving from the controller via said first and second bridge devices an indication of which of said temperature response elements caused the controller to generate the first interrupt signal and an indication of the current temperature of the temperature response elements that caused the controller to generate the first interrupt signal.

35. The thermal control system of claim 34 wherein first and second control tables are stored in main memory, the first control table specifying fan speed and the second control table specifying CPU clock signal frequency.

36. The thermal control system of claim 35 wherein the first control table includes a plurality of values that specify fan speed, each fan speed value associated with a range of temperatures of the second temperature response element.

37. The thermal control system of claim 35 wherein the second control table includes a plurality of values indicative of CPU clock signal frequency, each CPU clock signal frequency value associated with a range of temperatures of the first temperature response element.

38. The thermal control system of claim 37 wherein said controller is programmed with a range of temperatures from each of the first and second control tables and said controller compares the current temperatures received from the CPU to said range of temperatures programmed in the controller.

39. The thermal control system of claim 31 wherein said controller includes hysteresis to control the speed of said fan.