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5.3 Host Commands
*2) Advanced Power Management (APM)
The host writes the Sector Count field with the desired power management level
and executes this command with the Features field X’05’, and then Advanced
Power Management is enabled.
The drive automatically shifts to power saving mode up to the specified APM level
when the drive does not receive any commands for a specific time. The sequence in
which the power management level shifts is from Active Idle to Low Power Idle. The
Mode 0 level requires the longest shifting time, depending on the APM level settings.
The settings of the APM level revert to their default values (Mode-1) when power-on
or COMRESET occurs for the drive
.
APM Level Sector Count
Field
Mode 0 Active Idle → Low Power Idle
Mode 1 Active Idle
→ Low Power Idle
Mode 2 Active Idle
→ Low Power Idle
Reserve (State Keep)
C0h-FEh
80h-BFh
01h-7Fh
00h, FFh
Active Idle: The spindle motor rotates, and the head is loaded on
the most inner position on media.
Low Power Idle: The spindle motor rotates, and the head is unloaded.
C141-E249 5-123