Product manual

Barracuda 7200.7 Serial ATA Product Manual, Rev. C 15
2.9.2 Deferred spinup
Barracuda 7200.7 Serial ATA drives provide a deferred spinup feature which
storage 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 7200.7 Serial ATA disc drives will spin up only after power is
applied to the drive and after successful PHY (Physical layer) initialization.
PHY initialization 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 trans-
ceivers 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.