Conducted Noise Immunity; Power Sequencing; Current Profile - Seagate ST318203LW Product Manual

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[6] Operating condition is defined as random 8 block reads at 200 I/Os per second for ST318203 drive, 203 I/
Os per second for ST39103 drives, and 197 I/Os per second for ST318233 and ST39133 drives. Current
and power specified at nominal voltages. ST318203 and ST39103: Increasing +5 volts by +5% increases
5 volt current by < 0.5%. ST318233 and ST39133: Decreasing +5 volts by +5% increases 5 volt current by
2.7%. All Cheetah 18LP models: 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 Notes for Table 2:
1. Minimum current loading for each supply voltage is not less than 1.9% of the maximum operating current
shown.
2. The +5 and +12 volt supplies shall 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.
5. No terminator power.
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
Figures 3 and 4 identify the drive +12 V current profiles of drives documented in this manual. The current dur-
ing 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 18LP Product Manual, Rev. F