Seagate ST3160023AS, ST3120827AS, ST3120026AS, ST380817AS Typical current profiles, Deferred spinup

2.8.1.1Typical current profiles

+5 Volt Current during spindle start — Typical Amperes

1.50
1.25
1.00
Amps
0.75
0.50
0.25
0.0
0.0	2	4	6	8	10	12	14	16	18
					Seconds

Figure 1. Typical 5V startup and operation current profile

+12 Volt Current during spindle start — Typical Amperes

	2.4
	2.0
	1.6
Amps	1.2
	0.8
	0.4
	0.0
	0.0	2	4	6	8	10	12	14	16	18
						Seconds

Figure 2. Typical 12V startup and operation current profile

2.8.2Deferred 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) initializa- tion. PHY initialization occurs after the PHY enters the DP7:DR_Ready state. This state is reached after a suc-

Barracuda 7200.7 Serial ATA Product Manual, Rev. N 9