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Barracuda 36FC 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. Values indicated apply at the drive
connector.
Table 1:
DC power requirements
Voltage
Regulation
Avg idle current DCX
Maximum starting current
(peak DC) DC
(peak AC) AC
Delayed motor start (max) DC
Peak operating current:
Typical DCX
Maximum DC
Maximum (peak) DC
[1]
Measured with average reading DC ammeter. Instantaneous +12V current peaks will exceed these val-
ues. Power supply at nominal voltage.
For +12 V, a –10% tolerance is allowed during initial spindle start but must return to ±5% before reaching
[2]
7,200 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 208 I/Os per second. Current and power speci-
fied at nominal voltages. Increasing +5 volt supply by +5% increases 5 volt current by < 0.5%. Decreasing
+12 volt supply by 5% increases +12 volt current by 1.4%.
[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.
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.
4. Parameters, other than spindle start, are measured after a 10-minute warm up.
ST136475FC
Notes
(Amps)
+5V
[5]
±5%
[1] [7]
0.7
[3]
0.75
[3]
[1] [4]
0.55
[1] [6]
0.75
[1]
0.75
1.1
(Amps)
+12V [2]
±5% [2]
0.95
2.63
3.1
0.25
1.25
1.30
2.6
19
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