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Cheetah 10K.6 FC Product Manual, Rev. B 19
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. Instantaneous +12V current peaks will exceed these val-
ues. Power supply at nominal voltage. Number of drives tested = 6, 22 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 3.
[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 (ST3146807 at 234, ST373307 at 239 and
ST336607 at 239) I/Os per second. Current and power specified at nominal voltages. Decreasing +5 volt
supply by 5% increases 5 volt current by 3.6%. Decreasing +12 volt supply by 5% increases 12 volt cur-
rent by 3%.
[7] During idle, the drive heads are relocated every 60 seconds to a random location within the band from
track zero to one-fourth of maximum track.
[8] Values shown are for operation at 2 Gb; for operation at 1 Gb, reduce the +5V by 0.10 amps. The +12V
current values are not affected by loop speed.
General DC power requirement notes.
1. Minimum current loading for each supply voltage is not less than 0.8% of the maximum operating current
shown.
2. The +5V and +12V supplies should employ separate ground returns.
Table 1: DC power requirements
ST3146807FC ST373307FC ST336607FC
Notes (Amps) (Amps) (Amps) (Amps) (Amps) (Amps)
Voltage +5V [8] +12V [2] +5V [8] +12V [2] +5V [8] +12V [2]
Regulation [5] ±5% ±5% [2] ±5% ±5% [2] ±5% ±5% [2]
Avg idle current DC X
[1] [7]
0.92 0.51 0.91 0.37 0.93 0.27
Maximum starting current
(peak DC) DC 3σ [3]
1.09 1.48 1.02 1.26 0.99 1.04
(peak AC) AC 3σ [3]
1.38 2.61 1.36 2.30 1.30 1.94
Delayed motor start (max) DC 3σ [1] [4]
0.70 0.02 0.70 0.02 0.71 0.02
Peak operating current:
Typical DC X
[1] [6]
0.97 0.94 0.97 0.88 0.99 0.75
Maximum DC 3σ [1]
0.99 0.95 0.98 0.89 1.00 0.78
Maximum (peak) DC 3σ
1.50 2.40 1.54 2.30 1.46 2.06