Temperature sensor and method for detecting trip temperature of a temperature sensor

A temperature sensor, comprising:

• 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;
• first and second variable resistance circuits connected in series between the variable current node of the comparator and a supply voltage, wherein the first variable resistance circuit includes n resistors connected in series, where n is an integer of 4 or more and the n resistors have different resistance values, and wherein the second variable resistance circuit includes m resistors connected in series, where m is an integer of 4 or more and the m resistors have different resistance values;
• a first switching circuit which selectively bypasses individual ones of the n resistors of the first variable resistance circuit;
• and
• a second switching circuit which selectively bypasses individual ones of the m resistors of the second variable resistance circuit.

A temperature sensor, comprising:

• 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;
• a variable resistance circuit including a plurality of resistors connected in series;
• and
• a trimming circuit which selectively electrically connects or disconnects individual ones of the resistors of variable resistance circuit to the variable current node.

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, (b) a variable resistance circuit including at least resistors R1, R2, . . . Rn which are selectively connected in series between the variable current node of the comparator and a supply voltage, where n is an integer of 4 or more, and wherein R1<R2, . . . Rn-1<Rn, said method comprising:

• fixing a temperature of the temperature sensor to a first temperature, and electrically connecting the resistors R1, R2, . . . Rn in series between the variable current node of the comparator and a supply voltage;
• conducting a test sequence in which the output node of the comparator of the comparator is monitored while the resistor Rn is bypassed between the variable current node of the comparator and the supply voltage, and in which the resistor Rn is set to be electrically connected between the variable current node and the supply voltage if the output node of the comparator is the first voltage, and the resistor Rn is set to be bypassed between the variable current node and the supply voltage if the output node of the comparator is the second voltage;
• repeating the test sequence for each of the remaining resistors Rn-1 to R1 in order;
• and
• upon completion of the final test sequence for the resistor R1, determining a trip resistance of the temperature sensor as a difference between the first temperature and an adjustment temperature corresponding to a total value of the resistors R1, R2, . . . Rn which were set to be connected between the variable current node and the supply voltage.

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:

• conducting a first test which includes (a) fixing a temperature of the temperature sensor to a first reference temperature, and (b) increasing 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 first change in trip temperature of the sensor;
• conducting a second test which includes (a) fixing a temperature of the temperature sensor to a second reference temperature, and (b) decreasing 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 second change in trip temperature of the sensor;
• calculating the trip temperature according to the first and second reference temperatures and the first and second changes in trip temperature of the sensor.