Seagate ST373454 Manual download pdf (Page 32)

22 Cheetah 15K.3 SCSI Product Manual, Rev. G

[5] See Section 6.2.1 “Conducted Noise Immunity.” Specified voltage tolerance is inclusive of ripple, noise,

and transient response.

[6] Operating condition is defined as random 8 block reads at 307 (for ST373453 models) I/Os per second

(304 I/Os per second for ST336753 and ST318453 models). Current and power specified at nominal volt-

ages. Decreasing +5-volt supply by 5% increases 5-volt current by 3.2%. Decreasing +12-volt supply by

5% increases 12-volt current by 1.4% (2% for ST336753 and ST318453 models).

[7] During idle, the drive heads are relocated every 60 seconds to a random location within the band from

three-quarters to maximum track.

General Notes from Table 3:

1. Minimum current loading for each supply voltage is not less than 1.5% 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

starting 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.

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 for LW

model drives or optionally on the backplane on LC model drives. 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 for LW model drives or optionally on the backplane on LC model drives.

6.2.3 Current profile

Figures 2, 4 and 6 identify the drives +12 V current profile for each model. Figures 3, 5 and 7 identify the drives

+5 V current profile for each model.The current during the various times is as shown:

Note. All times and currents are typical. See Table 3 for maximum current requirements.

+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.

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.

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