Hitachi HUS154530VLF400 User Manual
Hitachi Ultrastar 15K450 (FC-AL) Hard Disk Drive Specification
5
3.0 Fixed-disk Subsystem Description
3.1 Control Electronics
The drive is electronically controlled by a microprocessor, logic modules, digital/analog modules and various drivers and
receivers. The control electronics perform the following major functions:
receivers. The control electronics perform the following major functions:
• Perform self-checkout (diagnostics)
• Conduct a power-up sequence and calibrate the servo.
• Monitor various timers for head settling, servo failure, etc.
• Analyze servo signals to provide closed-loop control. These include position error signal and estimated velocity.
• Control of the voice coil motor driver to align the actuator onto a desired position
• Monitor the actuator position and determine the target track for a seek operation.
• Constantly monitor error conditions of the servo and take corresponding action if an error occurs.
• Control starting, stopping, and rotating speed of the spindle.
• Control and interpretation of all interface signals between the host controller and the drive
• Control of read/write accessing of the disk media, including defect management and error recovery
3.2 Head Disk Assembly
The head/disk assembly (HDA) is assembled in a clean room environment and contains disks, a spindle motor, actuator assem-
bly, and voice coil motor. Air is constantly circulated and filtered when the drive is operational. Venting of the HDA is accom-
plished via a breather filter.
bly, and voice coil motor. 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 a brushless, sensorless DC drive motor. Dynamic braking is used to stop the spindle quickly.
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 data pattern supplies feedback to the
positioning servo to keep the read/write heads centered over the desired track.
closed-loop positioning servo controls the movement of the actuator. An embedded servo data 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.
Heads are moved out from the disks (unloaded) to protect the disk data during shipping, moving, or storage. At power down,
the heads are automatically unloaded from over the disk area and the head actuator locking mechanism will secure the heads in
the unload position.
the heads are automatically unloaded from over the disk area and the head actuator locking mechanism will secure the heads in
the unload position.