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6.2.1
Conducted noise immunity
Noise is specified as a periodic and random distribution of frequencies covering a band from DC to 10 MHz.
Maximum allowed noise values given below are peak to peak measurements and apply at the drive power con-
nector.
+5 V =
150 mV pp from 0 to 50 kHz and 100 mV pp from 50 kHz to 10 MHz.
+12 V =
150 mV pp from 0 to 50 kHz and 100 mV pp from 50 kHz to 10 MHz.
6.2.2
Power sequencing
The drive does not require power sequencing. The drive protects against inadvertent writing during power-up
and down. Daisy-chain operation requires that power be maintained on the terminated drive to ensure proper
termination of the peripheral I/O cables. To automatically delay motor start based on the target ID (SCSI ID)
enable the Delay Motor Start option and disable the Enable Motor Start option on the J2 connector. See Sec-
tion 8.1 for pin selection information. To delay the motor until the drive receives a Start Unit command, enable
the Enable Motor Start option on the J2 connector.
6.2.3
Current profile
Figures 3a and 3b identify the drive +5 V and +12 V current profile. The current during the various times is as
shown:
T -
Power is applied to the drive.
T1 -
Controller self tests are performed.
T2 -
Spindle begins to accelerate under current limiting after performing drive internal
diagnostics. See Note 1 of Table 2.
T3 -
The heads move from the landing zone to the data area.
T4 -
The adaptive servo calibration sequence is performed.
T5 -
Calibration is complete and the drive is ready for reading and writing.
Note.
All times and currents are typical. See Table 2 for maximum current requirements.
4.0
T
T1
3.5
3.0
2.5
2.0
+12V
1.5
Current
(amps)
1.0
0.0
0.0
Figure 3a.
Typical Barracuda 9LP family drive +12 V current profile
T3
T2
AC
Component
Nominal (average) DC curve
2
4
6
8
Barracuda 9LP Product Manual, Rev. C
T4
10
12
14
16
TIME (seconds)
T5
18
20
22
24
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