Product manual
Barracuda 9FC Product Manual, Rev. C 17
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.
[2] A –10% tolerance is allowed during initial spindle start but must return to ±5% before reaching 7,200
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] At power-up the motor current regulator limits the 12V current to an average value of less than 2.5 - 2.7A,
although instantaneous peaks may exceed this value. These peaks should measure 5 msec duration or
less.
[7] Operating condition means a third stroke seek at OD and Read One track. A command is issued every
0.062 seconds.
[8] Track following at track 0.
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.
Table 1: DC power requirements
ST19171FC
Voltage regulation Notes
[5]
+5V
±5V
(Amps)
+12V
±5V
[2]
(Amps)
Avg idle current [1] [8] 1.203 0.896
Max start current (peak DC) [3] [6] 1.108 2.216
Delayed motor start (max) [1] [4] 0.587 0.141
Operating current
Typical [1] [8] 1.044 1.015
Maximum [1] 1.071 1.043
Max (peak) 1.176 1.926