Fujitsu MAN3367FC - Enterprise 36.7 GB Hard Drive, Product/Maintenance Manual, Page: 105 / 148

8.3 Circuit Configuration
C141-E133-02EN 8-3
8.3 Circuit Configuration
Figure 8.1 shows the circuit configuration of IDD.
(1) Read/write circuit
The read/write circuit consists of 2 high performance LSIs, Read Channel and Head Preamp, which
perform reading and writing data. 32/34 Modified Extended EPRML (MEEPRML) is adopted as
recording method, which realizes high density recording.
(2) Servo circuit
Voice coil motor position/speed control is carried out by a closed loop servo system and carries out
feedback control based on servo information recorded on the data surface. Analog servo data is
converted into a digital signal, and is then processed by a DSP. The digital signal is then converted
into an analog signal which then controls the voice coil motor.
The DSP accurately controls traffic positioning of each head using servo information on the data
surface.
(3) Spindle motor drive circuit
The spindle motor drive circuit drives the spindle motor. A drive current in the motor coil generates
a counter-electromotive voltage. The frequency of the counter-electromotive voltage is compared, by
the DSP, with a reference frequency derived by dividing the oscillator frequency. The DSP uses the
result of the comparison to control the rotational frequency of the spindle motor.
(4) Controller circuit
The controller circuit has the following main functions:
•
Fibre channel control
•
Data buffering (8 Mbyte, 4 to 32 segments)
•
SCSI protocol control and data transfer control
•
Sector format control
•
ECC
•
Error recovery and self-diagnosis