On-chip over-temperature detection

An apparatus comprising:

• a plurality of heat generating circuits;
• a plurality of remote temperature sensors proximate the plurality of heat generating circuits;
• a main temperature sensor distal from the heat generating circuits;
• a processor adapted to:
• a) enable one of the plurality of heat generating circuits at a time,
• b) read at least one of the remote temperature sensors proximate the enabled heat generating circuit and the main temperature sensor while the one heat generating circuit is enabled,
• c) calculate a temperature difference, ΔT, between the main temperature sensor reading and the remote temperature sensor reading for each enabled heat generating circuit,
• d) disable, after calculating the temperature difference, the one heat generating circuit enabled in a
• e) determine which of the calculated ΔT is the largest ΔT, and
• f) calculate a trip-point temperature value, for use by an over-temperature detector responsive to the main temperature sensor, substantially equal to a known temperature limit value offset by the largest ΔT;
• wherein the plurality of heat generating circuits, the plurality of remote temperature sensors, and the main temperature sensor are located in one mixed-signal integrated circuit.

A method of operating an integrated circuit having a plurality of heat generating circuits and a plurality of remote temperature sensors proximate the plurality of heat generating circuits, and a main temperature sensor distal from the heat generating circuits, the method comprising the steps of:

• a) calibrating the main temperature sensor;
• b) enabling one of the plurality of heat generating circuits;
• c) reading at least one of the remote temperature sensors proximate the enabled heat generating circuit;
• d) reading the main temperature sensor;
• e) calculating a temperature difference, ΔT, between the main temperature sensor reading and the remote temperature sensor reading;
• f) disabling, after step et the one heat generating circuit enabled in step b);
• g) repeating steps b)-f) for each remaining heat generating circuit;
• h) determining the largest ΔT as calculated in step e);
• and
• i) setting a trip-point temperature value to a known temperature limit value offset by the largest ΔT;
• j) reading the main temperature sensor;
• and
• k) generating a signal when the main temperature sensor reading in step j) exceeds the trip-point temperature value;
• wherein only one heat generating circuit at a time is enabled in step b).