Product manual
24
Cheetah 15K.5 SCSI Product Manual, Rev. F
Table 4: ST3146855LC DC power requirements
Table 5: ST373455LC DC power requirements
[1] Measured with average reading DC ammeter or equivalent sampling scope. Instantaneous current peaks
will exceed these values. Power supply at nominal voltage. Number of drives tested = 6, 35 Degrees C
ambient.
[2] For +12 V, a –10% tolerance is permissible during initial start of spindle, and must return to ±5% before
15,000 rpm is reached. 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 +12 V current profile in Figure 1.
[4] This condition occurs when the Motor Start Option is enabled and the drive has not yet received a Start
Motor command.
[5] See Section 6.2.1 “Conducted Noise Immunity.” Specified voltage tolerance is inclusive of 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 Notes for Tables 3, 4, and 5:
1. Minimum current loading for each supply voltage is not less than 1.2% of the maximum operating current
shown.
2. The +5 and +12 volt supplies shall 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
Notes
LVD mode
Voltage +5 V +12 V
Regulation [5] ±5% ±5% [2]
Average idle current DC X [1][6] 0.71 0.57
Maximum starting current
(peak DC) DC
(peak AC) AC
3σ
3σ
[3]
[3]
0.74
1.04
1.94
3.32
Delayed motor start (max) DC
3σ
[1] [4] 0.56 0.03
Peak operating current
DC
Maximum DC
Maximum (peak) DC
X
3σ
3σ
[1]
[1]
0.67
0.68
1.42
0.88
0.94
2.50
Notes
LVD mode
Voltage +5 V +12 V
Regulation [5] ±5% ±5% [2]
Average idle current DC X [1][6] 0.69 0.42
Maximum starting current
(peak DC) DC
(peak AC) AC
3σ
3σ
[3]
[3]
0.72
1.00
1.94
3.32
Delayed motor start (max) DC
3σ
[1] [4] 0.56 0.03
Peak operating current
DC
Maximum DC
Maximum (peak) DC
X
3σ
3σ
[1]
[1]
0.67
0.68
1.40
0.78
0.82
2.38