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 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.

 

 

APM Level

Sector Count Field

 

 

 

Mode 0

Active Idle → Low Power Idle

C0h-FEh

Mode 1

Active Idle → Low Power Idle

80h-BFh

Mode 2

Active Idle → Low Power Idle → Standby

01h-7Fh

Reserve (State Keep)

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.

 

Standby:

The spindle motor stops, and the head is unloaded.

C141-E280

5-123