where RDSON(25) represents the resistance of FET 112 between the drain and source at 25??? C. when FET 112 operates in the on state, A is a well-known temperature coefficient of RDSON, and T is the temperature measured in centigrade of FET 112 operating in the on state at the time voltage VS is compared with the voltage VM. Using equation (2), equation (1) can be translated into: