Fujitsu MJA2500BH - Mobile 500 GB Hard Drive Product/Maintenance Manual page 197

*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 to
Standby. The Mode-2 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
Mode 0 Active Idle → Low Power Idle
Mode 1 Active Idle → Low Power Idle
Mode 2 Active Idle → Low Power Idle → Standby
Reserve (State Keep)
C141-E293
APM Level
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.
Standby: The spindle motor stops, and the head is unloaded.
5.3 Host Commands
.
Field
Sector Count
C0h-FEh
80h-BFh
01h-7Fh
00h, FFh
5-123