Patent ID: 7245098

Claim:
A motor drive circuit for a brushless dc motor, comprising: a PWM drive IC member electrically connected with a motor coil, the PWM drive IC member being capable of controlling a speed of the motor; a PWM converter circuit electrically connected with the PWM drive IC member for inputting a PWM signal; and a Rotational Detection (RD) signal line connected between the PWM drive IC member and the PWM converter circuit, said RD signal line further connected with a RD signal source; wherein when the motor is operated, said RD signal line supplies a RD signal between the PWM drive IC member and the PWM converter circuit; and wherein when the motor is jammed, said RD signal line supplies a RD signal to build a predetermined voltage between the PWM drive IC member and the PWM converter circuit so as to maintain the PWM drive IC member to be operated in a low-speed mode.