| 摘要 |
PURPOSE:To reduce the sizes of a motor and a motor drive circuit by detecting the presence or absence of an FG signal during rotating or stopping to turn ON or OFF the motor drive circuit. CONSTITUTION:An FG converter 3 converts an FG signal generated from an FG pattern 1 into a DC voltage corresponding to the rotating speed, and a voltage comparator 4 controls a Hall element drive transistor 5 in response to the output of the converter 3. A differentiated voltage corresponding to the dividing ratio of a capacitor C and a resistor R2 is generated at the starting time to turn a transistor Q1 ON and a transistor Q2 OFF, and the transistor 5 is released from muting. The transistor Q1 maintains ON state while a motor 9 is rotated to output the FG signal. When the FG signal is stopped, the transistor Q1 is turned OFF, and the transistor 5 is muted to stop the motor 9. |
