Seagate Elite 9, Product Manual

Page: 65 / 82

Elite 9 Product Manual, Rev. C 55
11.7.1.2.3 General cable characteristics
Note. Use only non-shielded cable connectors with ST410800N/ND drives.
Use a 50-conductor flat cable or 25-conductor twisted-pair cable. Use
a minimum conductor size of 28 AWG to minimize noise effects. The
following non-shielded flat cables (or equivalents) may be used:
Flat cable 28 AWG, 3M-3365-50
Flat cable 26 AWG, 3M-3801-50
Twisted-pair flat cable 28 AWG, 3M-1700-50
(differential or single-ended)
In general, cables having the characteristic impedances given in Sections
11.7.1.2.1 and 11.7.1.2.2 are not available; however, impedances that are
lower are satisfactory. A characteristic impedance of 100 ohm
+
10% is
recommended for unshielded flat or twisted-pair ribbon cable. To minimize
discontinuities and signal reflections, cables of different impedances should
not be used in the same bus. Your specific setup may require tradeoffs in
shielding effectiveness, cable length, number of loads, transfer rates, and
cost to achieve satisfactory system operation. If shielded and unshielded
cables are mixed within the same SCSI bus, the effect of impedance
mismatch must be carefully considered. Proper impedance matching is
especially important to maintain adequate margin at fast SCSI transfer rates.
11.7.2 Connector requirements
Use a non-shielded 50-conductor cable connector consisting of two rows of
25 female contacts with adjacent centers 100 mils apart.
Recommended mating flat cable connector part numbers:
Closed end 3M-3425-7000 Without strain relief, no center key
(for cable ends) 3M-3425-7600 Without strain relief, with center key
3M-3425-7050 With strain relief, no center key
3M-3425-7650 With strain relief, with center key
Open end 3M-3425-6000 Without strain relief, no center key
(in daisy chain) 3M-3425-6600 Without strain relief, with center key
3M-3425-6050 With strain relief, no center key
3M-3425-6650 With strain relief, with center key
The drive device connector is a non-shielded 50-conductor connector
consisting of two rows of 25 male pins with adjacent pins 100 mils apart. The
connector is keyed (see Figure 19).
11.7.3 Electrical description
ST410800N drives use single-ended interface signals and can be configured
to provide the SCSI termination.
ST410800ND drives use differential interface signals. Differential I/O drives
are shipped with removable terminators installed on the PCB.