Patent ID: 6323612
Filing Date: 2001-11-27
Classification: H02P

Abstract:
A motor driving device having a current limiter circuit that produces a current limit voltage different by a predetermined voltage from a driving voltage of a motor, the motor driving device performing a first operation whereby a driving current of the motor is controlled in accordance with a signal corresponding to an error of an actual rotation rate of the motor from a specified rotation rate thereof, the motor driving device performing, when the first operation requires that the driving current of the motor be higher than a predetermined level, a second operation whereby the driving current of the motor is controlled in accordance with the current limit voltage,wherein the current limiter circuit comprises a plurality of resistors for dividing a given voltage, a first transistor that receives at a base thereof a voltage obtained by voltage division achieved by the resistors, a constant current circuit for keeping an emitter current of the first transistor constant, a second transistor having a base thereof connected to an emitter of the first transistor, a resistor connected between an emitter of the second transistor and one of the higher- and lower-potential sides of the driving voltage of the motor, and a resistor connected between a collector of the second transistor and the other of the higher- and lower-potential sides of the driving voltage of the motor, the current limiter circuit outputting as the current limit voltage a collector voltage of the second transistor.