| 摘要 |
PURPOSE:To obtain a circuit for controlling the rotation of a spindle motor for a magnetic disc in which the motor is driven efficiently with low switching loss without causing useless power consumption. CONSTITUTION:A CPU 22 sets a device current supply interval (B/A) per one excitation phase depending on the difference between the r.p.m. of a motor 11, detected based on a rotor position signal RP from a rotor position detecting circuit 13, and a preset target r.p.m. When a time set signal St designating the actual driving time (B) is produced and delivered to a timing generation circuit 23, a drive timing signal Gt being turned ON at the actual driving time (B) in synchronism with the excitation timing of each exciting phase is fed to a motor drive circuit 21. A power supply voltage Vcc is then turned ON/OFF in synchronism with the drive timing signal Gt to deliver motor drive signals U, V, W, while switching sequentially, to respective coils of the motor 11 for each exciting phase. |
