Thermal management techniques in an electronic device

• US 8,554,389 B2
• Filed: 10/16/2012
• Issued: 10/08/2013
• Est. Priority Date: 05/30/2008
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Cox, Keith, Watson, Matthew G., Albert, Eric, West, Daniel Ariel, Novotney, Donald J., Culbert, Michael F., Just, Andrew Bradley, Powers, David Matthew
• Primary Examiner(s): Padmanabhan, Kavita
• Assistant Examiner(s): STEVENS, THOMAS H
• Application Number:
  US13/652,709
• Publication Number:
  US 20130041513A1
• Time in Patent Office: 357 Days
• Field of Search: 700/30, 700/31, 700/33, 700/299, 320/144, 320/150, 320/153, 420/62
• US Class Current: 700/299
• CPC Class Codes: G06F 1/203 for portable computers, e.g. for laptops
• CPC Class Codes: G06F 1/206 comprising thermal management
• CPC Class Codes: G06F 1/3203 Power management, i.e. event-based initiation of a power-saving mode
• CPC Class Codes: H04W 52/027 by controlling a display operation or backlight unit
• CPC Class Codes: Y02D 10/00 Energy efficient computing, e.g. low power processors, power management or thermal management
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

A thermal manager has a digital filter whose input is to receive raw temperature values from a sensor and whose output is to provide processed or filtered temperature values according to a filter function that correlates temperature at the sensor with temperature at another location in the device. The thermal manager has a look-up table that further correlates temperature at the sensor with temperature at the other location. The look-up table contains a list of processed temperature sensor values, and/or a list of temperatures representing the temperature at the other location, and their respective power consumption change commands. The thermal manager accesses the look-up table using selected, filtered temperature values, to identify their respective power consumption change commands. The latter are then evaluated and may be applied, to mitigate a thermal at the other location. Other embodiments are also described and claimed.

Claims

1. A method for thermal manage ent of an electronic device, comprising:

obtaining a plurality of temperature readings from a temperature sensor that is located in a device at a location that is remote from a target location in the device;

processing by a digital filter the plurality of temperature readings wherein the digital filter estimates a relationship over time between temperature at the remote location and temperature at the target location;

computing estimates of temperature at the target location using the processed temperature readings by converting the processed temperature readings using a predefined mathematical relationship between an estimated target location temperature variable and a processed temperature reading variable; and

using the computed estimates of the target location temperature to access a look up table and thereby identify power consumption commands, wherein the look up table contains a) a plurality of values all associated with the target location temperature and b) a plurality of power consumption commands, respectively, that include i) a plurality of no-change commands and ii) at least one change command that limits or reduces power consumption of a component in the device.

2. The method of claim 1 wherein the predefined mathematical relationship is a linear equation.

3. The method of claim 1 wherein the look up table contains at least one change command being a display backlight power limit.

4. The method of claim 3 wherein the look table contains a further change command being a kill application command.

5. The method of claim 1 wherein the look up table contains at least one change command being a kill application command.

6. The method of claim 1 wherein the predefined mathematical relationship between the estimated target location temperature variable and the processed temperature reading variable adjusts for different steady state temperatures of the sensor and of the target location.

7. The method of claim 6 wherein the predefined mathematical relationship is a linear relationship.

8. An electronic device comprising:

a temperature sensor at a first location of a device that is remote from a second location of the device; and

a thermal manager to process a plurality of temperature readings from the temperature sensor to obtain a plurality of processed temperature readings associated with the second location,

the thermal manager to (a) convert the processed temperature readings into estimates of temperature at the second location using a predefined mathematical relationship between an estimated target location temperature variable and a processed temperature reading variable, (b) compare the estimates to a desired temperature for the second location to determine errors, and (c) determine whether or not to apply a predefined, power consumption action that would reduce the errors.

9. The electronic device of claim 8 wherein the desired temperature encompasses a temperature range of up to two degrees Centigrade.

10. The electronic device of claim 8 wherein the second location is a battery hot spot of the device.

11. The electronic device of claim 10 wherein the first location is on or at an RF power amplifier of the device.

12. The electronic device of claim 8 wherein the second location is approximately a center location of a back case of the device.

13. The electronic device of claim 12 wherein the first location is on or at a battery of the device.

14. The electronic device of any one of claims 10, 11, 12, and 13 wherein the thermal manager is to convert the processed temperature readings into second location temperature estimates using a linear equation.

15. A method for thermal management of an electronics device, comprising:

estimating a temperature of a target location that is a battery hot spot or back case of the device using a temperature sensor that is at a remote location from the target location, by

(a) filtering a sequence of temperature readings from the temperature sensor that is at the remote location in the device, and

(b) using one of the filtered temperature readings to access a look up table, that lists temperature thresholds and corresponding power consumption commands, and thereby identify a power consumption command associated with a component of the device,

wherein the look up table correlates temperature at the temperature sensor with temperature at the target location in the device, and further wherein the corresponding power consumption commands include a plurality of no change commands and at least one change command that limits or reduces power consumption of a component in the device to achieve thermal mitigation at the target location.

16. The method of claim 15 further comprising:

repeating (b) so as to use another one of the filtered temperature readings to access the look up table, until said at least one change command is identified; and

applying the identified change command to limit or reduce power consumption of a component of the device.

17. The method of claim 15 wherein the list of temperature thresholds in the look up table refers to temperature at said target location of the device, and

wherein using the filtered temperature reading to access the look up table comprises converting, using a predefined mathematical relationship, the filtered temperature reading into a value that refers to temperature at said target location.

18. The method of claim 15 wherein the list of temperature thresholds in the look up table refers to filtered temperature readings, wherein using the filtered temperature readings comprises:

directly indexing into the look up table with the filtered temperature reading.