Seagate CHEETAH 15K.5 SCSI ST3146855LC User Manual

Page 29

Cheetah 15K.5 SCSI Product Manual, Rev. J

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 7.2.1 “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:

Minimum current loading for each supply voltage is not less than 1.2% of the maximum operating current
shown.

The +5 and +12 volt supplies shall employ separate ground returns.

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

[1][6]

0.71

0.57

Maximum starting current

(peak DC) DC

(peak AC) AC

[3]

0.74

1.04

1.94

3.32

Delayed motor start (max) DC

[1] [4]

0.56

0.03

Peak operating current

Maximum DC

Maximum (peak) DC

[1]

0.67

0.68

1.42

0.88

0.94

2.50