Digital thermal sensor test implementation without using main core voltage supply

A digital thermal sensor calibration apparatus in an analog voltage domain, the apparatus comprising:

• test circuit and a plurality of digital thermal sensors in a processor chip that are powered by an analog voltage without enabling a core voltage to any remaining components in the processor chip in order to eliminate any effect of self-heating due to leakage current in the remaining components of the processor chip, wherein the test circuit receives a clock signal;
• a register coupled to the test circuit outputs a value on each clock cycle from the clock signal to each digital thermal sensor in the plurality of digital thermal sensors;
• and
• for each digital thermal sensor in the plurality of digital thermal sensors:
• 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;
• 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.

A computer program product comprising a non-transitory computer readable medium having a computer readable program for calibrating digital thermal sensors in an analog voltage domain, wherein the computer readable program, when executed in a data processing system, causes the data processing system to:

• receive and power test logic and a plurality of digital thermal sensors, in a processor chip, with an analog voltage and without enabling a core voltage to any remaining components in the processor chip in order to eliminate any effect of self-heating due to leakage current in the remaining components of the processor chip;
• receive a clock signal;
• output a value of a register on each clock cycle from the clock signal to each digital thermal sensor in the plurality of digital thermal sensors;
• and
• for each digital thermal sensor in the plurality of digital thermal sensors:
• 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;
• 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.