Hitachi IC25N020ATMR04, Specifications

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Travelstar 80GN Hard Disk Drive Specification
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unloaded by routing the back EMF of the spinning motor to the voice coil. The actuator velocity is greater than the
normal case and the unload process is inherently less controllable without a normal seek current profile.
Emergency unload is intended to be invoked in rare situations. Because this operation is inherently uncontrolled, it
is more mechanically stressful than a normal unload.
The drive supports a minimum of 20,000 emergency unloads.
6.3.6.2 Required Power-Off Sequence
The required BIOS sequence for removing power from the drive is as follows:
Step 1: Issue one of the following command:
• Standby
• Standby immediate
• Sleep
Note: Do not use the Flush Cache command for the power off sequence because this command does not invoke
Unload.
Step 2: Wait until the Command Complete status is returned
In a typical case 350 ms are required for the command to finish completion; however, the BIOS time out value
needs to be 30 seconds considering error recovery time. Refer to Section 14.0, “Time-out values” on page 193.
Step 3: Terminate power to the drive
This power-down sequence should be followed for entry into any system power-down state, system suspend state,
or system hibernation state. In a robustly designed system, emergency unload is limited to rare scenarios, such as
battery removal during operation.
6.3.6.3 Power Switch design considerations
In systems that use this drive consideration should be given to the design of the system power switch.
Hitachi recommends that the switch operate under control of the BIOS rather than be hardwired. The same recom-
mendation is made for cover-close switches. When a hardwired switch is turned off, emergency unload occurs, as
well as the problems cited in Section 5.1, “Data loss at power off” on page 21 and Section 5.2, “Write Cache” on
page 21.
6.3.6.4 Test considerations
Start/stop testing is classically performed to verify head/disk durability. The heads do not land on the disk, there-
fore this type of test should be viewed as a test of the load/unload function.
Start/Stop testing should be done by commands through the interface, not by power cycling the drive. Simple
power cycling of the drive invokes the emergency unload mechanism and subjects the HDD to nontypical mechan-
ical stress.
Power cycling testing may be required to test the boot-up function of the system. In this case Hitachi recommends
that the power-off portion of the cycle contain the sequence specified in Section 6.3.6.2, “Required Power-Off
Sequence” on page 30. If this is not done, the emergency unload function is invoked and nontypical stress results.