4.7.1Servo control circuit

Figure 4.4 is the block diagram of the servo control circuit. The following describes the functions of the blocks:

Head

(2)

Servo burst capture

(1)

MPU

(3)

ADC DSP unit

 

SVC

(4)

 

(5)

 

 

VCM current

DAC

P.

Amp.

 

 

 

 

CSR

Position Sense

CSR: Current Sense Resistor

VCM: Voice Coil Motor

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

VCM

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

(6)

 

(7)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Spindle

 

 

Driver

 

Spindle

motor

 

 

 

 

 

 

motor

control

 

 

 

 

 

 

 

 

 

 

 

 

 

Figure 4.4 Block diagram of servo control circuit

(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).

C141-E112-01EN

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Fujitsu MPG3XXXAH manual Servo control circuit