Servo Control; Servo Control Circuit; Block Diagram Of Servo Control Circuit - Fujitsu MPG3XXXAH-E Product Manual

4.7

Servo Control

The actuator motor and the spindle motor are submitted to servo control. The actuator motor is
controlled for moving and positioning the head to the track containing the desired data. To turn
the disk at a constant velocity, the actuator motor is controlled according to the servo data that is
written on the data side beforehand.
4.7.1

Servo control circuit

Figure 4.4 is the block diagram of the servo control circuit. The following describes the functions
of the blocks:
(2)
Servo
burst
Head
capture
Position Sense
CSR: Current Sense Resistor
VCM: Voice Coil Motor
(1) Microprocessor unit (MPU)
The MPU includes DSP unit, etc., and the MPU starts the spindle motor, moves the heads to the
reference cylinders, seeks the specified cylinder, and executes calibration according to the internal
operations of the MPU.
The major internal operations are listed below.
a. Spindle motor start
Starts the spindle motor and accelerates it to normal speed when power is applied.
MPU
(3)
DSP
ADC
unit
Figure 4.4

Block diagram of servo control circuit

C141-E116-01EN
(1)
SVC
(4) (5)
P.
DAC
Amp.
(6) (7)
Spindle
Driver
motor
control
VCM current
CSR
VCM
Spindle
motor
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