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Seagate Enterprise Capacity 3.5 HDD v4 Serial ATA Product Manual, Rev. C 13
2.5.2 Conducted noise
Input noise ripple is measured at the host system power supply across an equivalent 80-ohm resistive load on the +12 V line
or an equivalent 15-ohm resistive load on the +5V line.
• Using 12V power, the drive is expected to operate with a maximum of 120mV peak-to-peak square-wave injected noise at
up to 10MHz.
• Using 5V power, the drive is expected to operate with a maximum of 100mV peak-to-peak square-wave injected noise at
up to 10MHz.
2.5.3 Voltage tolerance
Voltage tolerance (including noise):
5V +10/ -5% 12V ± 10%
2.5.4 Extended Power Conditions - PowerChoice
TM
Utilizing the load/unload architecture a programmable power management interface is provided to tailor systems for reduced
power consumption and performance requirements.
The table below lists the supported power conditions available in PowerChoice. Power conditions are ordered from highest
power consumption (and shortest recovery time) to lowest power consumption (and longest recovery time) as follows: Idle_a
power >= Idle_b power >= Idle_c power >= Standby_z power. The further users go down in the table, the more power
savings is actualized. For example, Idle_b results in greater power savings than the Idle_a power condition. Standby results
in the greatest power savings.
Each power condition has a set of current, saved and default settings. Default settings are not modifiable. Default and saved
settings persist across power-on resets. The current settings do not persist across power-on resets. At the time of
manufacture, the default, saved and current settings are in the Power Conditions log match.
PowerChoice is invoked using one of two methods
• Automatic power transitions which are triggered by expiration of individual power condition timers. These timer values may
be customized and enabled using the Extended Power Conditions (EPC) feature set using the standardized Set Features
command interface.
• Immediate host commanded power transitions may be initiated using an EPC Set Features "Go to Power Condition" sub-
command to enter any supported power condition. Legacy power commands Standby Immediate and Idle Immediate also
provide a method to directly transition the drive into supported power conditions.
PowerChoice exits power saving states under the following conditions
• Any command which requires the drive to enter the PM0: Active state (media access)
• Power on reset
PowerChoice provides the following reporting methods for tracking purposes
Check Power Mode Command
• Reports the current power state of the drive
Identify Device Command
• EPC Feature set supported flag
• EPC Feature enabled flag is set if at least one Idle power condition timer is enabled
Note
Equivalent resistance is calculated by dividing the nominal voltage by the typical RMS read/write current.
Power Condition Name Power Condition ID Description
Idle_a 81
H
Reduced electronics
Idle_b 82
H
Heads unloaded. Disks spinning at full RPM
Idle_c 83
H
Heads unloaded. Disks spinning at reduced RPM
Standby_z 00
H
Heads unloaded. Motor stopped (disks not spinning)