Predictive temperature compensation for memory devices systems and method

• US 6,557,072 B2
• Filed: 05/10/2001
• Issued: 04/29/2003
• Est. Priority Date: 05/10/2001
• Status: Expired due to Term

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Palm, Inc. (TCL Technology Group Corp.)
• Inventors: Osborn, Neal A.
• Primary Examiner(s): Bragdon, Reginald G.
• Assistant Examiner(s): Baker, Paul A.
• Application Number:
  US09/853,132
• Publication Number:
  US 20020169924A1
• Time in Patent Office: 719 Days
• Field of Search: 702/130-132, 365/222, 365/212, 711/106
• US Class Current: 711/106
• 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 mobile electronic device is disclosed. The mobile electronic device includes a housing, a processor supported by the housing, and a memory device coupled to the processor, the memory device including an adjustable self-refresh rate setting configured to determine the self-refresh rate of the memory device. The mobile electronic device also includes a temperature sensor supported by the housing, the temperature sensor is coupled to the processor and configured to measure a temperature. The mobile electronic device also includes computer program logic running on the processor, and the computer program logic is configured to predict a future temperature and change the adjustable self-refresh rate setting based on the predicted future temperature.

Claims

1. A mobile electronic device, comprising:

a housing;

a processor supported by the housing;

a memory device coupled to the processor, the memory device including an adjustable self-refresh rate setting configured to determine the self-refresh rate of the memory device;

a temperature sensor supported by the housing, coupled to the processor and configured to measure a temperature; and

computer program logic running on the processor, and configured to predict a future temperature and change the adjustable self-refresh rate based on the predicted future temperature.

2. The mobile electronic device of claim 1, wherein the temperature is measured at a periodic rate.

3. The mobile electronic device of claim 2, wherein the periodic rate is greater than one (1) second.

4. The mobile electronic device of claim 2, wherein the periodic rate is greater than five (5) seconds.

5. The mobile electronic device of claim 2, wherein the periodic rate is greater than ten (10) seconds.

6. The mobile electronic device of claim 2, wherein the periodic rate is greater than thirty (30) seconds.

7. The mobile electronic device of claim 2, wherein the periodic rate is based on the thermal profile of the mobile electronic device.

8. The mobile electronic device of claim 7, wherein the thermal profile is determined empirically.

9. The mobile electronic device of claim 1, wherein the computer program logic uses the difference between a current temperature reading and a previous temperature reading to calculate a predicted temperature reading.

10. The mobile electronic device of claim 1, wherein the memory device is a low power synchronous dynamic random access memory (LPDRAM) device.

11. A method of changing the self-refresh rate for a memory circuit having an adjustable refresh rate, comprising:

defining a temperature compensated self-refresh rate (TCSR) value;

measuring a temperature associated with the temperature of the memory circuit;

providing a new TCSR value if the temperature is greater than the current TCSR value;

storing the current temperature reading with at least one other previous temperature reading;

calculating a predicted temperature reading based on the current temperature and the at least one other previous temperature reading; and

providing a new TCSR value if the predicted temperature is greater than the current TCSR value.

12. The method of claim 11, further comprising:

lowering the TCSR setting if the current temperature reading is less than the current TCSR and the predicted temperature is less than the current temperature reading.

13. The method of claim 11, wherein the measuring a temperature step is carried out at a periodic rate.

14. The method of claim 13, wherein the periodic rate is based on the thermal properties of a device within which the LPDRAM circuit resides.

15. The method of claim 13, further comprising:

establishing a desired periodic rate based on empirical results.

16. The method of claim 11, further comprising:

providing a new TCSR value if the temperature is equal to the current TCSR value.

17. The method of claim 11, further comprising:

providing a new TCSR value if the predicted temperature is equal to the current TCSR value.

18. The method of claim 11, wherein the memory circuit is a low power synchronous dynamic random access memory (LPDRAM) circuit.

19. A handheld computer, comprising:

a housing;

a display supported by the housing;

a processor supported by the housing and coupled to the display;

low power synchronous dynamic random access memory (LPDRAM) coupled to the processor, the LPDRAM including a temperature compensated self-refresh rate (TCSR) setting configured to determine the self-refresh rate of the LPDRAM;

a temperature sensor supported by the housing, coupled to the processor and configured to measure a temperature; and

computer program logic running on the processor, and configured to predict a future temperature and change the TCSR based on the predicted future temperature.

20. The handheld computer of claim 19, wherein the temperature is measured at a periodic rate.

21. The handheld computer of claim 20, wherein the periodic rate is greater than one (1) second.

22. The handheld computer of claim 20, wherein the periodic rate is based on the thermal profile of the handheld computer.

23. The handheld computer of claim 22, wherein the thermal profile is determined empirically.

24. The handheld computer of claim 19, wherein the computer program logic uses the difference between a current temperature reading and a previous temperature reading to calculate the predicted temperature.

25. The handheld computer of claim 19, wherein the computer program logic uses linear interpolation of the current temperature and a previous temperature to calculate the predicted future temperature.

26. The handheld computer of claim 19, wherein the computer program logic uses quadratic fitting of the current temperature and at least two other temperatures to calculate the predicted future temperature.