Patent ID: 7038415

Claim:
A motor driving circuit comprising: a semiconductor switching element interposed in a current flowing passage to a motor; a PWM control unit for generating a PWM signal having a predetermined PWM frequency; a driving circuit for making the semiconductor switching element carry out a switching operation under plural driving states, and driving the semiconductor switching element in PWM (Pulse Width Modulation) mode according to the PWM signal under an instructed driving state; an overheat state detecting unit for outputting an overheat state detecting signal on a condition that a temperature of the semiconductor switching element exceeds a predetermined threshold value and the semiconductor switching element falls into an overheat state or a state in which the probability that the semiconductor switching element will shift to the overheat state is higher than a predetermined probability; and a driving control unit for instructing the driving state of the semiconductor switching element to the driving circuit so that the rise time and fall time of the semiconductor switching element during an output period of the overheat state detecting signal are shorter than the rise time and fall time of the semiconductor switching element during a non-output period of the overheat state detecting signal.