Servo Control; Servo Control Circuit; Block Diagram Of Servo Control Circuit - Fujitsu MPF3XXXAT 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
Figure 4.4
(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.
4 - 12
(1)
MPU
(3)
DSP
ADC
unit

Block diagram of servo control circuit

C141-E099-01EN
SVC
(4) (5)
VCM current
P.
DAC
Amp.
(6) (7)
Spindle
Driver
motor
control
CSR
VCM
Spindle
motor