Conducted Noise Immunity; Power Sequencing; Current Profile - Seagate ST318404LW Product Manual

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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 100 kHz and 100 mV pp from 100 kHz to 10 MHz.
+12 V = 150 mV pp from 0 to 100 kHz and 100 mV pp from 100 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 SCSI bus terminator 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
Section 8.1 for pin selection information. To delay the motor until the drive receives a Start Unit command,
enable the Enable Remote Motor Start option on the J2 connector.
6.2.3 12 V - Current profile
Figure 3 identifies the drive +12 V current profile. The current during the various times is as shown:
T0 - 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 spindle is up to speed and the head-arm restraint is unlocked.
T4 - The adaptive servo calibration sequence is performed.
T5 - Calibration is complete and drive is ready for reading and writing.
Note. All times and currents are typical. See Table 2 for maximum current requirements.
Cheetah 18XL Product Manual, Rev. A