Seagate ST3300955FC, ST3400755FC manual General DC power requirement notes

Table 3:	DC power requirements for ST3300955FC model
				1 Gbit		2 Gbit		4 Gbit
			Notes	(Amps)	(Amps)	(Amps)	(Amps)	(Amps)	(Amps)
Voltage				+5V	+12V [2]	+5V	+12V [2]	+5V	+12V [2]
Regulation			[5]	±5%	±5% [2]	±5%	±5% [2]	±5%	±5% [2]
			[1] [7]	0.70	0.31	0.72	0.31	0.78	0.31
Avg idle current DCX
Maximum starting current
(peak DC) DC		3σ	[3]	0.80	1.78	0.82	1.78	0.88	1.78
(peak AC) AC		3σ	[3]	1.07	3.25	1.14	3.25	1.30	3.26
Delayed motor start (max) DC		3σ	[1] [4]	0.59	0.03	0.62	0.03	0.68	0.03
Peak operating current:
			[1] [6]	0.73	0.63	0.74	0.63	0.80	0.65
Typical DCX
Maximum DC		3σ	[1]	0.73	0.69	0.75	0.67	0.81	0.67
Maximum (peak) DC		3σ		1.32	2.52	1.36	2.50	1.44	2.54

[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 10,000 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 profiles in Figures 1 and 2.

[4]This condition occurs when the Motor Start option is enabled and the drive has not yet received a Start Motor command.

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

[6]Operating condition is defined as random 8 block reads at 309 s I/Os per second for ST3400755FC and 314 I/Os per second for ST3300955FC models. Current and power specified at nominal voltages. Decreasing +5 volt supply by 5% increases 5 Volt current by 3.5%. Decreasing +12 volt supply by 5% increases 12 volt current by 2.5% (1.5% for ST3300955FC models).

[7]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 1.2% 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 Cheetah NS FC Product Manual, Rev. B