Theory of Device Operation
4.7.5 Spindle motor control
(1) Start mode
When power is supplied, the spindle motor is started in the following sequence:
a)After the power is turned on, the MPU sends a signal to the SVC to charge the charge pump capacitor of the SVC. The charged amount defines the current that flows in the spindle motor.
b)When the charge pump capacitor is charged enough, the MPU sets the SVC to the motor start mode. Then, a current (approx. 0.3 A) flows into the spindle motor.
c)A phase switching signal is generated and the phase of the current flowed in the motor is changed in the order of
d)During phase switching, the spindle motor starts rotating in low speed, and generates a counter electromotive force. The SVC detects this counter electromotive force and reports to the MPU using a PHASE signal for speed detection.
e)The MPU is waiting for a PHASE signal. When no phase signal is sent for a specific period, the MPU resets the SVC and starts from the beginning. When a PHASE signal is sent, the SVC enters the acceleration mode.
(2) Acceleration mode
In this mode, the MPU stops to send the phase switching signal to the SVC. The SVC starts a phase switching by itself based on the counter electromotive force. Then, rotation of the spindle motor accelerates. The MPU calculates a rotational speed of the spindle motor based on the PHASE signal from the SVC, and waits till the rotational speed reaches 5,400 rpm. When the rotational speed reaches 5,400 rpm, the SVC enters the stable rotation mode.
