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Cheetah NS SAS Product Manual, Rev. B
23
6.0 Physical/electrical specifications
This section provides information relating to the physical and electrical characteristics of the drive.
6.1 AC power requirements
None.
6.2 DC power requirements
The voltage and current requirements for a single drive are shown below. Values indicated apply at the drive
connector.
[1] Measured with average reading DC ammeter or equivalent sampling scope. Instantaneous +12V current
peaks will exceed these values. 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 profile in Figure 19.
[4] This condition occurs after OOB and Speed Negotiation completes but before the drive has received the
Notify Spinup primitive.
Table 2: ST3400755SS DC power requirements
Notes
ST3400755SS
1.5 Gbit mode
ST3400755SS
3 Gbit mode
(Amps) (Amps) (Amps) (Amps)
Voltage +5V +12V [2] +5V +12V [2]
Regulation [5] ±5% ±5% [2] ±5% ±5% [2]
Avg idle current DCX
[1] [6] 0.76 0.37 0.75 0.37
Maximum starting current
(peak DC) DC 3σ [3] 0.89 1.73 0.88 1.73
(peak AC) AC 3σ [3] 1.10 3.43 1.14 3.40
Delayed motor start (max) DC 3σ [1] [4] 0.63 0.04 0.67 0.04
Peak operating current:
Typical DCX
[1] 0.75 0.69 0.78 0.68
Maximum DC 3σ [1] 0.78 0.74 0.81 0.74
Maximum (peak) DC 3σ 1.38 2.64 1.40 2.58