Servo Control Circuit - Fujitsu MPG3XXXAH Product Manual

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.
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).
MPU
(3)
DSP
ADC
unit
Figure 4.4 Block diagram of servo control circuit
C141-E112-01EN
(1)
SVC
(4) (5)
P.
DAC
Amp.
(6) (7)
Spindle
Driver
motor
control
VCM current
CSR
VCM
Spindle
motor
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