Servo Control Circuit; Block Diagram Of Servo Control Circuit - Fujitsu MPB3021AT Product Manual

4.7.1

Servo control circuit

Figure 4.7 is the block diagram of the servo control circuit. The following describes the
functions of the blocks:
(2)
Servo
Head burst
capture
Position Sense
CSR: Current Sense Resistor
VCM: Voice Coil Motor
Figure 4.7
(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.
b. Move head to reference cylinder
Drives the VCM to position the head at the any cylinder in the data area. The logical
initial cylinder is at the outermost circumference (cylinder 0).
4 - 16
(1)
MPU
(3)
DSP
ADC
unit

Block diagram of servo control circuit

C141-E045-02EN
SVC
(4) (5)
VCM current
P.
DAC
Amp.
(6) (7)
Spindle
Driver
motor
control
CSR
VCM
Spindle
motor