| 摘要 |
PURPOSE:To reduce the affection of the number of rotation and increase reliability by a method wherein an overcurrent reference signal is changed in accordance with the number of rotation to slow down the rise-up of a driving current by an affection due to the counter electromotive force of a coil. CONSTITUTION:When the rotation of a DC motor is started, a reference voltage generating circuit 13 outputs an overcurrent reference signal 14 in accordance with the number of the rotation. The reference voltage generating circuit 13 outputs the overcurrent reference signal 14, showing the maximum current of a power source, when the number of rotation is low or the affection of a counter electromotive force generated by the coil of the DC motor is little and the rise-up of a current detecting signal 10 is quick. However, the average current of the power source is reduced and the supplying capacity of the power source becomes capable of being satisfied when the number of rotation is increased and the rise-up of the current detecting signal 10 is slowed down by the affection of the counter electromotive force generated by the coil of the DC motor. |
