THERMAL MANAGEMENT TECHNIQUES IN AN ELECTRONIC DEVICE

• US 20090299543A1
• Filed: 02/13/2009
• Published: 12/03/2009
• Est. Priority Date: 05/30/2008
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: West, Daniel Ariel, Just, Andrew Bradley, Powers, David, Novotney, Donald J., Culbert, Michael F., Albert, Eric, Cox, Keith, Watson, Matthew G.
• Granted Patent: US 8,315,746 B2
• Time in Patent Office: Days
• 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 said another location. The look-up table contains a list of processed temperature sensor values, and/or a list of temperatures representing the temperature at said another 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 said another location. Other embodiments are also described and claimed.

Claims

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

monitoring the temperature of a target location in the device without having a temperature sensor at that location, by

(a) filtering a sequence of temperature readings from a temperature sensor that is at a 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 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, wherein the look up table correlates temperature at the temperature sensor with temperature at said target location in the device.

2. The method of claim 1 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.

3. The method of claim 1 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.

4. The method of claim 1 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.

5. The method of claim 2 wherein applying the identified change command to the component of the device comprises:

limiting RF transmit power of a cellular network transceiver in the device to a level that is indicated by the identified change command.

6. The method of claim 2 wherein applying the identified change command to the component of the device comprises:

reducing light output of a display screen backlight in the device to a level that is indicated by the identified change command.

7. The method of claim 1 wherein applying the identified change command to the component of the device comprises:

reducing clock frequency or supply voltage of a data processing unit in the device to a level that is indicated by the identified change command.

8. A method for thermal management of an electronic device, comprising:

reading a first temperature sensor that is located in the device near a first component of the device and far from a second component of the device;

reading a second temperature sensor that is located in the device near the second component and far from the first component; and

changing the limit on power output by the first component, in accordance with said reading the second temperature sensor.

9. A method for thermal management of an electronic device, comprising:

reading a first temperature sensor that is located in the device closer to a first component of the device than second and third components of the device;

reading a second temperature sensor that is located in the device closer to the second component than the first and third components; and

correlating readouts from the first temperature sensor with readouts from the second temperature sensor to extrapolate temperature of a selected one of the first, second and third components, and on that basis changing a power consumption limit of the selected component.

10. An electronic device comprising:

a temperature sensor; and

a thermal manager having a digital filter whose input is to receive raw temperature values from the sensor and whose output is to provide processed temperature values according to a filter function that correlates temperature at the sensor with temperature at another location in the device,

the thermal manager having a look-up table that further correlates temperature at the sensor with temperature at said another location, the look-up table having a list of temperature values, representing a temperature range at the sensor or at said another location, and a plurality of power consumption change commands associated with the list of temperature values, respectively,

the thermal manager to access the look-up table a plurality of times, each time using a different one of processed temperature values, to identify a plurality of power consumption change commands and evaluate the identified plurality of power consumption change commands to determine what change, if any, should be commanded to the power consumption of a component in the device.

11. The electronic device of claim 10 further comprising:

a wireless communications transceiver RF power amplifier, wherein one of the identified power consumption change commands is an RF output power limit on the power amplifier.

12. The electronic device of claim 10 further comprising:

a display screen having a backlight, wherein one of the identified power consumption change commands is a brightness limit on the backlight.

13. The electronic device of claim 10 further comprising:

a central processing unit, CPU, wherein one of the identified power consumption change commands is a processor clock limit or supply voltage limit on the CPU.

14. The electronic device of claim 10 wherein the thermal manager comprises memory in which is stored a history of temperature readings from the sensor that have been correlated to temperature of said another location,

the thermal manager to consult the stored history and on that basis alter the strength of the change that is commanded to the power consumption of the component in the device.

15. An electronic device comprising:

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

a thermal manager to process a sequence of temperature readings from the temperature sensor to obtain a sequence of processed temperature readings,

the thermal manager having a look up table that lists a plurality of temperature thresholds associated with a plurality of power consumption commands, respectively, wherein the 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,

the thermal manager to select a plurality of the processed temperature readings and use each selected processed reading to access the look up table and thereby identify a power consumption command, and to evaluate the identified power consumption command to determine what change, if any, should be commanded to mitigate a thermal event in the device.

16. The electronic device of claim 15 wherein the second location is a location whose temperature behavior, in response to an input heat source at the first location, is substantially different than that of the first location.

17. The electronic device of claim 15 wherein the thermal manager is to implement hysteresis such that as the device cools off, an identified power consumption command from the look up table that increases power consumption of a component in the device is not resumed immediately but rather is delayed until the device cools off further.

18. The electronic device of claim 15 wherein the power consumption commands in the look up table include at least one that alerts a user of the device about temperature in the device, by showing a graphic on a display screen of the device.

19. The electronic device of claim 15 wherein the plurality of temperature thresholds listed in the look up table are in the range 50-65 degrees Centigrade.

20. An electronic device comprising:

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

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

the thermal manager to (a) select a plurality of the processed temperature readings and convert each selected processed reading into an estimate of temperature at the second location, (b) compare the estimate to a desired temperature for the second location to determine an error, and (c) evaluate the determined error to determine whether or not a predefined, power consumption action that would reduce the error needs to be applied.

21. The electronic device of claim 20 wherein the desired temperature ranges up to two degrees Centigrade.