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12 Barracuda Serial ATA V Product Manual, Rev. B
2.9.2 Deferred spinup
Barracuda Serial ATA V drives provide a deferred spinup feature which stor-
age subsystem controllers can use to sequence disc drive initialization. This
is beneficial to systems which include multiple Serial ATA hard disc drives
because it allows subsystem controllers to stagger the spinup of each drive
to accommodate available power supply current. This feature does not
impact time-to-ready in typical desktop systems.
To accommodate the deferred spinup of multiple disc drives in an enclosure,
Barracuda Serial ATA V disc drives will spin up only after power is applied to
the drive and after successful PHY (Physical layer) initialization. PHY initial-
ization occurs after the PHY enters the DP7:DR_Ready state. This state is
reached after a successful exchange of Out-Of-Band (OOB) signals with a
functional host-side Serial ATA port. In desktop systems, SATA transceivers
should initialize OOB as soon as power comes ready to guarantee the drive
spins up quickly. Seagate disc drives will not spin up without an operational
host-side Serial ATA transceiver.
Additional details
Upon system power up, PHY communication is initiated with a COMRESET
signal, which is generated by the host-side transceiver. COMRESET is fol-
lowed by a COMINIT signal generated by the disc drive transceiver. COMRE-
SET and COMINIT are followed by an exchange of COMWAKE signals and
Align primitives. The disc drive will spin up after the successful exchange of
Align primitives cause the PHY to come ready.
For more details, refer to:
• Section 6.8 of the Serial ATA 1.0 High-Speed Serialized AT Attachment
specification
• Section 6.2 of the Serial ATA II: Extensions to Serial ATA 1.0 specification
• SATA 1.0 design guides
Note. These specifications and guides are available on the Serial ATA web
site (www.serialata.org).
2.9.3 Conducted noise
Input noise ripple is measured at the host system power supply across an
equivalent 80-ohm resistive load on the +12 volt line or an equivalent 15-ohm
resistive load on the +5 volt line.
• Using 12-volt power, the drive is expected to operate with a maximum of
120 mV peak-to-peak square-wave injected noise at up to 10 MHz.