Conducted Noise Immunity; Power Sequencing; Current Profile - Seagate ST3146854LC - Cheetah 146.8 GB Hard Drive User Manual

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
connector.
+5 V = 250 mV pp from 0 to 100 kHz to 20 MHz.
+12 V = 800 mV pp from 100 Hz to 8 KHz.
450 mV pp from 8 KHz to 20 KHz.
250 mV pp from 20 KHz to 5 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 supplied to 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 on LW mod-
els or on the backplane for LC models. 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 on
LW models or on the backplane for LC models.
6.2.3

Current profile

Figures 2 through 7 show the current profiles for each model.
All times and currents are typical. See Table 12 for maximum current requirements.
Cheetah 15K.4 SCSI Product Manual, Rev. D 27