Hitachi HDS728080PLAT20 Specifications - Page 23

Fixed-disk subsystem description - driver

Page 23 highlights

3.0 Fixed-disk subsystem description 3.1 Control electronics The drive is electronically controlled by a microprocessor, several logic modules, digital/analog modules, and various drivers and receivers. The control electronics performs the following major functions: • Controls and interprets all interface signals between the host controller and the drive. • Controls read write accessing of the disk media, including defect management and error recovery. • Controls starting, stopping, and monitoring of the spindle. • Conducts a power-up sequence and calibrates the servo. • Analyzes servo signals to provide closed loop control. These include position error signal and estimated velocity. • Monitors the actuator position and determines the target track for a seek operation. • Controls the voice coil motor driver to align the actuator in a desired position. • Constantly monitors error conditions of the servo and takes corresponding action if an error occurs. • Monitors various timers such as head settle and servo failure. • Performs self-checkout (diagnostics). 3.2 Head disk assembly The head disk assembly (HDA) is assembled in a clean room environment and contains the disks and actuator assembly. Air is constantly circulated and filtered when the drive is operational. Venting of the HDA is accomplished via a breather filter. The spindle is driven directly by an in-hub, brushless, sensorless DC drive motor. Dynamic braking is used to quickly stop the spindle. 3.3 Actuator The read/write heads are mounted in the actuator. The actuator is a swing-arm assembly driven by a voice coil motor. A closed-loop positioning servo controls the movement of the actuator. An embedded servo pattern supplies feedback to the positioning servo to keep the read/write heads centered over the desired track. The actuator assembly is balanced to allow vertical or horizontal mounting without adjustment. When the drive is powered off, the actuator automatically moves the head to the actuator ramp outside of the disk where it parks. Deskstar 7K80 Hard Disk Drive Specification 19

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Deskstar 7K80 Hard Disk Drive Specification
19
3.0
Fixed-disk subsystem description
3.1
Control electronics
The drive is electronically controlled by a microprocessor, several logic modules, digital/analog modules, and var-
ious drivers and receivers. The control electronics performs the following major functions:
Controls and interprets all interface signals between the host controller and the drive.
Controls read write accessing of the disk media, including defect management and error
recovery.
Controls starting, stopping, and monitoring of the spindle.
Conducts a power-up sequence and calibrates the servo.
Analyzes servo signals to provide closed loop control. These include position error signal and
estimated velocity.
Monitors the actuator position and determines the target track for a seek operation.
Controls the voice coil motor driver to align the actuator in a desired position.
Constantly monitors error conditions of the servo and takes corresponding action if an error
occurs.
Monitors various timers such as head settle and servo failure.
Performs self-checkout (diagnostics).
3.2
Head disk assembly
The head disk assembly (HDA) is assembled in a clean room environment and contains the disks and actuator
assembly. Air is constantly circulated and filtered when the drive is operational. Venting of the HDA is accom-
plished via a breather filter.
The spindle is driven directly by an in-hub, brushless, sensorless DC drive motor. Dynamic braking is used to
quickly stop the spindle.
3.3
Actuator
The read/write heads are mounted in the actuator. The actuator is a swing-arm assembly driven by a voice coil
motor. A closed-loop positioning servo controls the movement of the actuator. An embedded servo pattern supplies
feedback to the positioning servo to keep the read/write heads centered over the desired track.
The actuator assembly is balanced to allow vertical or horizontal mounting without adjustment.
When the drive is powered off, the actuator automatically moves the head to the actuator ramp outside of the disk
where it parks.