Seagate ST973451SS manual ST936751SS DC power requirements, General DC power requirement notes

Table 3:	ST936751SS DC power requirements
				ST936751SS		ST936751SS
				1.5 Gbit mode		3.0 Gbit mode
			Notes	(Amps)	(Amps)	(Amps)	(Amps)
Voltage				+5V	+12V [2]	+5V	+12V [2]
Regulation			[5]	±5%	±5% [2]	±5%	±5% [2]
			[1] [6]	0.77	0.16	0.74	0.16
Avg idle current DCX
Maximum starting current
(peak DC) DC		3σ	[3]	0.85	1.33	0.81	1.28
(peak AC) AC		3σ	[3]	1.27	1.87	1.11	1.87
		3σ
Delayed motor start (max) DC			[1] [4]	0.63	0.03	0.67	0.03
Operating current:
			[1]	0.75	0.34	0.78	0.34
Typical DCX
Maximum DC		3σ	[1]	0.78	0.38	0.81	0.37
Maximum (peak) DC		3σ		1.46	1.14	1.52	1.16

[1]Measured with average reading DC ammeter. Instantaneous +12V current peaks will exceed these val- ues. Power supply at nominal voltage. N (number of drives tested) = 6, 35 Degrees C ambient.

[2]For +12 V, a –10% tolerance is allowed during initial spindle start but must return to ±5% before reaching 9,936 RPM. The ±5% must be maintained after the drive signifies that its power-up sequence has been completed and that the drive is able to accept selection by the host initiator.

[3]See +12V current profile in Figure 1.

[4]This condition occurs after OOB and Speed Negotiation completes but before the drive has received the Notify Spinup primitive.

[5]See paragraph 6.2.1, "Conducted noise immunity." Specified voltage tolerance includes ripple, noise, and transient response.

[6]During idle, the drive heads are relocated every 60 seconds to a random location within the band from three-quarters to maximum track.

General DC power requirement notes.

1.Minimum current loading for each supply voltage is not less than 1.7% of the maximum operating current shown.

2.The +5V and +12V supplies should employ separate ground returns.

3.Where power is provided to multiple drives from a common supply, careful consideration for individual drive power requirements should be noted. Where multiple units are powered on simultaneously, the peak starting current must be available to each device.

4.Parameters, other than spindle start, are measured after a 10-minute warm up.

5.No terminator power.

24 Savvio 15K SAS Product Manual, Rev. B