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11.46.4 Advanced Power Management
When the value in the Feature register is 05h (=Enable Advanced Power Management), the Sector Count Register
specifies the Advanced Power Management level.
FFh ---
Aborted
C0 – FEh ---
The deepest power saving mode is Idle mode
(the same as Disable Advanced Power Management)
80 – BFh ---
The deepest power saving mode is Low power Idle mode
01 – 7Fh ---
The deepest power saving mode is Low RPM Idle mode
00h ---
Aborted
The idle time to Low power idle mode and Low RPM idle mode vary according to the value in Sector Count Register
as follows:
When Low power idle mode is the deepest power saving mode,
Y
=(x-80h) * 5+120
1
Y
=N/A(the device does not go to Low RPM idle mode)
2
When Low RPM idle mode is the deepest power saving mode and the value in Sector Count Register is between
40h and 7Fh,
120<=Y
<=435 [sec] (default: 120 [sec])
1
Y
=(x-40h) * 60 + 600[sec]
2
When Low RPM idle mode is the deepest power saving mode and the value in Sector Count Register is between
01h and 3Fh,
120<=Y
<=435 [sec] (default: 120 [sec])
1
Y
=600 [sec]
2
Where x is the value in Sector Count Register, y
Low RPM idle mode.
If Low power idle mode has already been enabled (i.e., y
preserved. If Low power idle mode is disabled (i.e., y
idle mode is enabled.
Enabled power saving mode and idle time (y
the deepest power saving mode becomes Idle mode, or new time is set. They are initialized with a hard/soft reset
unless Reverting to power on defaults is disabled and the device receives a soft reset.
11.46.5 Set Maximum Host Interface Sector Time
Sector Count
Typical PIO Mode Host Interface Sector Time (7:0)
LBA Low
Typical PIO Mode Host Interface Sector Time (15:8)
LBA Mid
Typical DMA Mode Host Interface Sector Time (7:0)
LBA High
Typical DMA Mode Host Interface Sector Time (15:8)
Subcommand code 43h allows the host to inform the device of a host interface rate limitation. The typical Host
Interface Sector Times have the same units as Identify Device word 96 for DMA and word 104 for PIO. A value of
zero indicates that the host interface shall be capable of transferring data at the maximum rate allowed by the
selected transfer mode. The Typical PIO Mode Host Interface Sector Time includes the host's interrupt service
time.
Y
[sec]
(120<=
<=435)
1
(600<=Y
<=4380)
2
and y
1
Western Digital Hard Disk Drive OEM Specification
is the idle time to Low Power Idle mode, and y
1
has been set) before Low RPM idle mode is enabled, y
1
has not been set yet), y
1
) are preserved until Advanced Power Management is disabled,
2
244
is the idle time to
2
becomes 120[sec] when Low RPM
1
is
1
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