PEAK HOLD CIRCUIT, MOTOR DRIVE/CONTROL CIRCUIT HAVING THE SAME, AND MOTOR APPARATUS HAVING THE SAME

摘要

A peak hold circuit capable of stably operating even when a peak voltage of a motor drive current detection voltage to be held is very small. The peak hold circuit (14) comprises a level shift circuit (50) for shifting the motor drive current detection voltage by a given voltage; a differential amplifier circuit (60) for receiving an output voltage from the level shift circuit (50) and the voltage of an output terminal (OUT) to amplify and then output the difference therebetween; an output transistor (81) for receiving at its base the output voltage from the differential amplifier circuit (60) to output, from its emitter, a charging current; a capacitor (82) charged by the charging current for holding the voltage of the output terminal (OUT); a bias element (84) for generating a voltage that is substantially equal to the given voltage of the level shift circuit (50); and a resistor element (83) disposed between the bias element (84) and the output terminal (OUT) for controlling the discharging current of the capacitor (82).