Patent ID: 6937087

Claim:
A method of determining a trip temperature of a temperature sensor, the temperature sensor having (a) a comparator circuit having an output node and a variable current node, wherein the output node is a first voltage at a given temperature when a current at the variable current node is less than a threshold current, and a different second voltage at the given temperature when the current at the variable current node is more than the threshold current, and (b) a variable resistance circuit connected in series between the variable current node of the comparator and a reference voltage, said method comprising: fixing a temperature of the temperature sensor to a reference temperature; varying a resistance of the variable resistance circuit to determine a difference between an initial resistance and a resistance at which the output node of the comparator oscillates between the first and second voltages, said difference corresponding to a change in trip temperature of the sensor; calculating the trip temperature according to the reference temperature and the change in trip temperature of the sensor.