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Barracuda 18FC Product Manual, Rev. B
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. On-board +3.3V current is derived on
the drive. Values indicated apply at the drive connector. Parameters, other than spindle start, are measured
after a 10-minute warm-up.
Table 1:
DC power requirements
Voltage regulation
Avg idle current
Max start current (peak DC)
Delayed motor start (max)
Operating current:
Typical
Maximum
Max (peak)
[1]
Measured with average reading DC ammeter. Instantaneous +12V current peaks will exceed these val-
ues.
A –10% tolerance is allowed during initial spindle start but must return to ±5% before reaching 7,200
[2]
RPM. The ±5% must be maintained after the drive signifies that its power-up sequence has been com-
pleted 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 seek reads of 64 blocks.
[7]
All power saving features enabled.
[8]
During idle, the heads are relocated every 60 seconds to a random location within the band from track 0 to
one-fourth of maximum track. This will result in a random variation in the +12 volt idle current of 0.0152
Amperes (0.182 Watts).
General DC power requirement notes.
1. Minimum current loading for each supply voltage is not less than 4% 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 start-
ing current must be available to each device.
ST118273FC
+5V
+12V
±5%
±5%[2]
Notes [5]
(Amps)
(Amps)
[1] [7] [8]
1.50
0.80
[3]
1.70
3.1
[1] [4]
1.45
0.03
[1] [6]
1.65
1.25
[1]
1.70
1.30
2.00
3.1
19
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