To reduce the cost of a motor driver concerning the motor driver for driving a DC motor.
A PID controller 3 receives the input of a current detection signal of its having detected the drive current of the motor 2 and a command signal. The motor driver 1 controls the drive current of the motor 2 by this PID controller 3. Passive elements such as at least a resistor, a capacitor, etc., constituting the PID controller 3, are mounted on a sub board. This sub board can be inserted into or extracted from the socket of a main board whereon switching circuits (including Q1-Q4) for supplying the motor 2 with a current and others are mounted. The motor driver is provided with a command value control element 6 which switches the gain of a command value by a gain switching signal and inputs it into the PID controller 3, and a command value limiter 7 which limits the command value inputted from the command value control element 6 into the PID controller 3 so that it may not get over a setting range.
KINOSHITA OSAMU
Shoji Kashiwaya
Koichi Watanabe
Toshiro Ito