Digital Thermal Sensor Test Implementation Without Using Main Core Voltage Supply

• US 20090125267A1
• Filed: 11/08/2007
• Published: 05/14/2009
• Est. Priority Date: 11/08/2007
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Johns, Charles R., Riley, Mack W., Wang, Michael F., Shan, David W.
• Granted Patent: US 8,027,798 B2
• Time in Patent Office: Days
• US Class Current: 702/99
• CPC Class Codes: G01K 15/00 Testing or calibrating of thermometers
• CPC Class Codes: G01K 15/005 Calibration

Abstract

A method and apparatus are provided for calibrating digital thermal sensors. A processor chip with a plurality of digital thermal sensors receives an analog voltage. A test circuit coupled to the processor chip receives a clock signal and a register coupled to the test circuit outputs a value on each clock cycle to a digital thermal sensor in the plurality of digital thermal sensors. The digital thermal sensor transitions an output state in response to the value of the register received in the digital thermal sensor equaling a temperature threshold of the digital thermal sensor. The value of the register at the point of transition is used to calibrate the digital thermal sensor. An incrementer increments the value of the register on each clock cycle in response to the value of the register received in the digital thermal sensor failing to equal the temperature threshold of the digital thermal sensor.

Claims

1. A method for calibrating digital thermal sensors, the method comprising:

receiving, in a processor chip with a plurality of digital thermal sensors, an analog voltage;

receiving a clock signal;

outputting a value of a register on each clock cycle to a digital thermal sensor in the plurality of digital thermal sensors; and

responsive to the value of the register received in the digital thermal sensor equaling a temperature threshold of the digital thermal sensor, transitioning an output state of the digital thermal sensor, wherein the value of the register at the point of transition is used to calibrate the digital thermal sensor.

2. The method of claim 1, further comprising:

responsive to the value of the register received in the digital thermal sensor failing to equal the temperature threshold of the digital thermal sensor, incrementing the value of the register on each clock cycle from the clock signal, wherein the value of the register is incremented by one on each clock cycle by an incrementer.

3. The method of claim 2, wherein incrementing the value of the register on each clock cycle from the clock signal is performed in response to receiving a start signal indicating a second state.

4. The method of claim 1, further comprising:

receiving a start signal indicating a first state that initiates a test mode; and

responsive to receiving the start signal indicating the first state, holding the start signal in the first state for a predetermined number of clock cycles so that the value of the register sets to zero, wherein the predetermined number of clock cycles is determined by a size of the register.

5. The method of claim 1, wherein a delta value that indicates the calibration value of the digital thermal sensor is stored in a data structure in a thermal management control unit.

6. The method of claim 5, wherein the delta value indicates a difference between the value of the register at the point of transition and a manufacturer'"'"'s test fixture temperature.

7. The method of claim 5, wherein the delta value is used to calibrate the temperatures sensed by the digital thermal sensor in a functional mode.

8. The method of claim 1, wherein the processor chip is placed in a manufacturer'"'"'s test fixture and is given time to stabilize to a test temperature of the manufacturer'"'"'s test fixture.

9. The method of claim 1, wherein the digital thermal sensor is set to an initial thermal threshold.

10. The method of claim 1, wherein calibrating the digital thermal sensor is performed without applying a core voltage to the processor chip.

11. A digital thermal sensor calibration apparatus, the apparatus comprising:

a processor chip that receives an analog voltage, wherein a plurality of digital thermal sensors are coupled to the processor chip;

a test circuit coupled to the processor chip that receives a clock signal;

a register coupled to the test circuit outputs a value on each clock cycle to a digital thermal sensor in the plurality of digital thermal sensors; and

the digital thermal sensor transitions an output state in response to the value of the register received in the digital thermal sensor equaling a temperature threshold of the digital thermal sensor, wherein the value of the register at the point of transition is used to calibrate the digital thermal sensor.

12. The apparatus of claim 11, further comprising:

an incrementer increments the value of the register on each clock cycle from the clock signal in response to the value of the register received in the digital thermal sensor failing to equal the temperature threshold of the digital thermal sensor, wherein the value of the register is incremented by one on each clock cycle.

13. The apparatus of claim 12, wherein incrementing the value of the register on each clock cycle from the clock signal is performed in response to receiving a start signal indicating a second state.

14. The apparatus of claim 11, wherein the test circuit receives a start signal that indicates a first state that initiates a test mode and wherein the value of the register sets to zero in response to the start signal being held in the first state for a predetermined number of clock cycles, wherein the predetermined number of clock cycles is determined by a size of the register.

15. The apparatus of claim 11, wherein a delta value that indicates the calibration value of the digital thermal sensor is stored in a data structure in a thermal management control unit.

16. The apparatus of claim 15, wherein the delta value indicates a difference between the value of the register at the point of transition and a manufacturer'"'"'s test fixture temperature.

17. The apparatus of claim 15, wherein the delta value is used to calibrate the temperatures sensed by the digital thermal sensor in a functional mode.

18. The apparatus of claim 11, wherein the processor chip is placed in a manufacturer'"'"'s test fixture and is given time to stabilize to a test temperature of the manufacturer'"'"'s test fixture.

19. The apparatus of claim 11, wherein the digital thermal sensor is set to an initial thermal threshold.

20. The apparatus of claim 11, wherein calibrating the digital thermal sensor is performed without applying a core voltage to the processor chip.

21. A computer program product comprising a computer useable medium having a computer readable program, wherein the computer readable program, when executed in a data processing system, causes the data processing system to:

receive, in a processor chip with a plurality of digital thermal sensors, an analog voltage;

receive a clock signal;

output a value of a register on each clock cycle to a digital thermal sensor in the plurality of digital thermal sensors; and

responsive to the value of the register received in the digital thermal sensor equaling a temperature threshold of the digital thermal sensor, transition an output state of the digital thermal sensor, wherein the value of the register at the point of transition is used to calibrate the digital thermal sensor.

22. The computer program product of claim 21, wherein the computer readable program further causes the data processing system to:

responsive to the value of the register received in the digital thermal sensor failing to equal the temperature threshold of the digital thermal sensor, increment the value of the register on each clock cycle from the clock signal, wherein the value of the register is incremented by one on each clock cycle by an incrementer, wherein incrementing the value of the register on each clock cycle from the clock signal is performed in response to receiving a start signal indicating a second state.

23. The computer program product of claim 21, wherein the computer readable program further causes the data processing system to:

receive a start signal indicating a first state that initiates a test mode; and

responsive to receiving the start signal indicating the first state, hold the start signal in the first state for a predetermined number of clock cycles so that the value of the register sets to zero, wherein the predetermined number of clock cycles is determined by a size of the register.

24. The computer program product of claim 21, wherein a delta value that indicates the calibration value of the digital thermal sensor is stored in a data structure in a thermal management control unit, wherein the delta value indicates a difference between the value of the register at the point of transition and a manufacturer'"'"'s test fixture temperature, and wherein the delta value is used to calibrate the temperatures sensed by the digital thermal sensor in a functional mode.

25. The computer program product of claim 21, wherein the processor chip is placed in a manufacturer'"'"'s test fixture and is given time to stabilize to a test temperature of the manufacturer'"'"'s test fixture, wherein the digital thermal sensor is set to an initial thermal threshold, and wherein calibrating the digital thermal sensor is performed without applying a core voltage to the processor chip.