An integrated circuit implements an on chip thermal circuit (12) for measuring temperature of an operating integrated circuit die (10) by requiring only one dedicated integrated circuit pin (16). A second integrated circuit pin (18) is utilized but is also connected directly connected to other circuitry (14) on the integrated circuit and is used by the other circuitry at the same time that the integrated circuit die temperature is being measured. In one form, the second integrated circuit pin is a ground terminal. Error voltages coupled to the ground terminal may be removed from the temperature calculation by an external differential amplifier (24).