Seagate ST910021AS, ST980825AS manual Typical current profiles, Deferred spinup, Additional details

2.9.1.1Typical current profiles

Figure 1. Typical 5V startup and operating current profile

2.9.2Deferred spinup

Momentus 7200.1 SATA 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, Momentus 7200.1 SATA disc drives will spin up only after power is applied to the drive and after successful PHY (Physical layer) initializa- tion. PHY initialization occurs after the PHY enters the DP7:DR_Ready state. This state is reached after a suc- cessful 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 followed by a COMINIT signal generated by the disc drive transceiver. COMRESET 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).

Momentus 7200.1 SATA Product Manual, Rev. B 9