Deferred Spinup; Figure 1. Typical 5V Startup And Operation Current Profile; Figure 2. Typical 12V Startup And Operation Current Profile - Seagate ST3160023AS - Barracuda 160 GB Hard Drive Product Manual

2.8.1.1 Typical 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

Figure 1. Typical 5V startup and operation current profile

2.4
2.0
1.6
Amps
1.2
0.8
0.4
0.0
0.0 2

Figure 2. Typical 12V startup and operation current profile

2.8.2

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) 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
6 8 10 12 14
Seconds
+12 Volt Current during spindle start — Typical Amperes
4 6 8 10 12
Seconds
16 18
18
14 16
9