Abstract: A semiconductor integrated circuit (IC) acts as a controller of a heating-controlled device or appliance. A heating body has a positive temperature coefficient and acts as both a heating element and a temperature sensor. A Silicon-Controlled Rectifier (SCR) switches AC current to the heating body to increase its temperature. When the SCR switches off, temperature sensing is performed using a sampling resistor, isolation diode, voltage comparator, and switch for a low-voltage DC supply are formed on an integrated circuit that has a first circuit branch and a second circuit branch. A compensation diode and a compensation resistor can be added in parallel to reference resistors. The compensation diode compensates for the forward voltage drop of the isolation diode that would otherwise create an inaccurate temperature measurement. The diodes have the same temperature response, allowing for a more accurate temperature measurement over a full temperature range of the sensorless appliance.

Abstract: A semiconductor integrated circuit (IC) acts as a controller of a heating-controlled device or appliance. A heating body has a positive temperature coefficient and acts as both a heating element and a temperature sensor. A Silicon-Controlled Rectifier (SCR) switches AC current to the heating body to increase its temperature. When the SCR switches off, temperature sensing is performed using a sampling resistor, isolation diode, voltage comparator, and switch for a low-voltage DC supply are formed on an integrated circuit that has a first circuit branch and a second circuit branch. A compensation diode and a compensation resistor can be added in parallel to reference resistors. The compensation diode compensates for the forward voltage drop of the isolation diode that would otherwise create an inaccurate temperature measurement. The diodes have the same temperature response, allowing for a more accurate temperature measurement over a full temperature range of the sensorless appliance.