Barracuda 18LP Family: ST39175LW/LC ST318275LW ... - Seagate
Barracuda 18LP Family: ST39175LW/LC ST318275LW ... - Seagate
Barracuda 18LP Family: ST39175LW/LC ST318275LW ... - Seagate
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20 <strong>Barracuda</strong> <strong>18LP</strong> Product Manual, Rev. E<br />
6.2.1 Conducted noise immunity<br />
Noise is specified as a periodic and random distribution of frequencies covering a band from DC to 10 MHz.<br />
Maximum allowed noise values given below are peak to peak measurements and apply at the drive power connector.<br />
+5 V = 150 mV pp from 0 to 50 kHz and 100 mV pp from 50 kHz to 10 MHz.<br />
+12 V = 150 mV pp from 0 to 50 kHz and 100 mV pp from 50 kHz to 10 MHz.<br />
6.2.2 Power sequencing<br />
The drive does not require power sequencing. The drive protects against inadvertent writing during power-up<br />
and down. Daisy-chain operation requires that power be maintained on the terminated drive to ensure proper<br />
termination of the peripheral I/O cables. To automatically delay motor start based on the target ID (SCSI ID)<br />
enable the Delay Motor Start option and disable the Enable Motor Start option on the J2 connector. See Section<br />
8.1 for pin selection information. To delay the motor until the drive receives a Start Unit command, enable<br />
the Enable Motor Start option on the J2 connector.<br />
6.2.3 Current profile<br />
Figures 3a and 3b identify the drive +5 V and +12 V current profile. The current during the various times is as<br />
shown:<br />
T -<br />
T1 -<br />
T2 -<br />
T3 -<br />
T4 -<br />
T5 -<br />
Power is applied to the drive.<br />
Controller self tests are performed.<br />
Spindle begins to accelerate under current limiting after performing drive internal<br />
diagnostics. See Note 1 of Table 2.<br />
The heads move from the landing zone to the data area.<br />
The adaptive servo calibration sequence is performed.<br />
Calibration is complete and the drive is ready for reading and writing.<br />
Note.<br />
All times and currents are typical. See Table 2 for maximum current requirements.<br />
3.5<br />
3.0<br />
2.5<br />
2.0<br />
T<br />
T3<br />
T1 T2 T4<br />
AC<br />
Component<br />
T5<br />
+12V<br />
Current<br />
(amps)<br />
1.5<br />
1.0<br />
0.5<br />
0.0<br />
Nominal (average) DC curve<br />
0.0 2 4 6 8 10 12 14 16 18 20 22 24<br />
TIME (seconds)<br />
Figure 3a.<br />
Typical <strong>Barracuda</strong> <strong>18LP</strong> family drive +12 V current profile