Threshold-based temperature-dependent power/thermal management with temperature sensor calibration
A method and apparatus for temperature sensor calibration is disclosed. In one embodiment, an integrated circuit (IC) is tested at a first known temperature corresponding to a first temperature threshold. During the test, a first temperature reading is obtained from a temperature sensor. A first offset is calculated by determining the difference between the first known temperature and the first temperature reading. The first offset is recorded in a storage unit for later use during operation of the IC. During operation, the first offset may be added to temperature readings obtained from a temperature sensing unit to produce an adjusted temperature value. The adjusted temperature value may be compared to one or more temperature thresholds. Based on the comparisons, a power management unit may perform power control actions.
1. A method comprising:
performing tests an integrated circuit (IC) at a first specified temperature;
reading a first temperature value provided by a temperature sensor during testing during testing at the first temperature;
determining a first offset value, wherein the first offset value is a difference between the first specified temperature and the first temperature value;
recording the first offset value;
repeating the testing for one or more additional specified temperatures including a second specified temperature;
reading one or more additional temperature values provided by the temperature sensor, including a second temperature value, during each iteration of said testing;
determining one or more corresponding additional offset values, including a second offset value; and
recording each of the one or more corresponding additional offset values.
2. The method as recited in claim 1 , further comprising recording the first and second offset values and each of the one or more additional offset values in a fuse unit, wherein recording each of the first and second offset values and the one or more additional offset values by blowing one or more fuses.
3. The method as recited in claim 1 , further comprising:
reading an operational temperature value from the temperature sensor;
determining an actual temperature value by adding the operational temperature value to the first offset value; and
determining whether the actual temperature value exceeds the first specified temperature, wherein the first specified temperature is a threshold value.
4. The method as recited in claim 3 , further comprising:
a power management unit requesting an external power supply to provide a first operating voltage IC if the actual temperature value exceeds the first specified temperature; and
the power management unit requesting the external power supply to provide a second operating voltage to the IC if the actual temperature value is less than the first specified temperature.
5. A method comprising:
performing a plurality of tests of an integrated circuit, wherein each of the plurality of tests is performed at one of a plurality of known temperature values;
reading, during each of the plurality of tests, one of a plurality of detected temperature values output by a temperature sensing unit;
determining a plurality of offset values, wherein each of the plurality of offset values corresponds to a calculated difference between one of the known temperature values and a corresponding one of the plurality of detected temperature values;
storing each of the plurality of offset values; and
determining an offset variation slope based on the plurality of offset values.
6. The method as recited in claim 5 , further comprising:
receiving a temperature reading from the temperature sensing unit during operation of the integrated circuit;
calculating a first operational temperature by adding the temperature reading and a first one of the plurality of offset values;
determining if the first operational temperature exceeds a first temperature threshold; and
maintaining a supply voltage at a first voltage value if the first operational temperature is less than the first temperature threshold.
7. The method as recited in claim 6 , further comprising a power management unit request a reduction of the supply voltage to a second voltage value if the first operational temperature exceeds the first temperature threshold.
8. The method as recited in claim 6 , further comprising:
calculating a second operational temperature, wherein calculating the second operational temperature comprises adding the temperature reading to a second one of the plurality of offset values;
determining if the second operational temperature exceeds a second temperature threshold; and
performing a shutdown of the integrated circuit is the second operational temperature exceeds the second threshold.