4.7.1Servo control circuit
Figure 4.5 is the block diagram of the servo control circuit. The following describes the functions of the blocks:
(1)
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Head |
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| Position Sense |
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CSR: Current Sense Resistor
VCM: Voice Coil Motor
SVC |
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(4) | (5) | VCM current | |
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DAC |
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Spindle | Driver | Spindle | |
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control |
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Figure 4.5 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).
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