Patent ID: 8383992

Claim:
A controllable heating pad, comprising: a heating conductor embedded in the heating pad; a sensing conductor embedded in the heating pad; a resistive material providing a distributed electrical path between the heating conductor and the sensing conductor; a first current sensor to sense a current in the heating conductor, the first current sensor including: a first current sense resistor having a first terminal forming an input to the first current sensor, and a second terminal, wherein the second terminal of the first current sense resistor is connected to a reference potential; a diode having a first terminal connected to the first terminal of the first current sense resistor; a first filter having a first terminal connected to a second terminal of the diode, and a second terminal connected to the second terminal of the first current sense resistor, wherein the first terminal of the first filter forms the first current sensor output; and a second current sensor to sense a current in the sensing conductor.