Driving circuit and driving method thereof

A driving circuit is used for driving a motor with a first coil and a second coil. The driving circuit comprises a pole changing unit, an operating unit and a control unit. The pole changing unit is coupled with the first coil and the second coil respectively. The operation unit is coupled with the pole changing unit, the first coil and the second coil respectively. The pole changing unit receives a commutation signal generated by the control unit to drive the motor to run. The control unit detects the rotation speed of the motor. When the rotation speed of the motor is larger than a preset rotation speed, the control unit outputs a first operation signal to the operation unit so as to couple first ends of the first coil and the second coil and to couple second ends of the first coil and the second coil; and when the rotation speed of the motor is less than the preset rotation speed, the control unit outputs a second operation signal to the operation unit so as to couple the second end of the first coil with the first end of the second coil.