Servo Control; Servo Control Circuit; Block Diagram Of Servo Control Circuit - Fujitsu MAF3364FC SERIES Maintenance Manual

5.7

Servo Control

The servomechanism is controlled using a digital servo technique by the firmware in the digital
signal processor (DSP).
DPS carries out VCM control. Control of the voice coil motor consists of track-following
operation control and seek operation control. Track-following operation is controlled to center
the data-head-mounted actuator over the target cylinder for read/write operation. The seek
operation moves the actuator to a different target cylinder at high speed. For stable operation, a
variety of calibration is done (see Section 5.5).
5.7.1

Servo control circuit

Figure 5.5 is the block diagram of the servo control circuit. The following explains each function
of the servo control circuit.
Servo system block diagram
Data surface
signal
Data Servo
bus8
head demodulator
bus8
HDC
(1) Processor-application specific IC (Processor-ASIC)
A DSP controls the spindle motor and the voice coil motor. The SCSI sends an instruction to the
DSP through the SCSI control MCU and native interface. The DSP is a 1-chip Processor-ASIC,
and also contains an analog-to-digital converter, a digital-to-analog converter, RAM, and other
logic circuits.
5 - 12
Processor
DSP
Core
bus16
Drive
bus16
I/F LSI
bus8
MCU
FMC16
Notes: DSP controlled actuator servo system
MCU controlled spindle servo system
Figure 5.5

Block diagram of servo control circuit

C141-F037-02EN
Control signal
(PWM)
SPM/VCM
combo
Control signal
FET 2 VCM
FET 3 Spindle
motor