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58
Table 14:
Interface transfer rates supported
Interface type/
drive models
SE
ST373453LW/LC
ST336753LW/LC
ST318453LW/LC
LVD
ST373453LW/LC
ST336753LW/LC
ST318453LW/LC
9.6.3
SCSI interface cable requirements
The characteristics of cables used to connect parallel interface drives are discussed in the ANSI standards ref-
erenced in this section.
9.6.3.1
Cable requirements
The characteristics of cables used to connect Ultra160 and Ultra320 SCSI parallel interface devices are dis-
cussed in detail in section 6 of the SPI-4 (ANSI T10/1365D) standard. The cable characteristics that must be
considered when interconnecting the drives described in this manual in a SCSI parallel, daisy-chain intercon-
nected system are:
• characteristic impedance (see T10/1365D Rev. 8 Sections 6.3.3, 6.3.4, and 6.3.5)
• propagation delay (see T10/1365D Rev. 8 Sections 6.3.6 and 6.3.7)
• cumulative length (see T10/1365D Rev. 8 Sections 6.6 and 6.8)
• stub length (see T10/1365D Rev. 8 Sections 6.6 and 6.9)
• device spacing (see T10/1365D Rev. 8 Sections 6.6 and 6.9)
To minimize discontinuances and signal reflections, cables of different impedances should not be used on the
same bus. Implementations may require trade-offs in shielding effectiveness, cable length, number of loads
and spacing, 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 in order to maintain adequate margin at Fast-20, Fast-40,
Fast-80, and Fast-160 SCSI transfer rates.
Note.
For LVD operation, twisted pair cables are recommended. For LVD Fast-40 operation, twisted pair
cables are strongly recommended. For Fast-80 or Fast-160 operation, twisted pair cables are required .
All LC model drives:
The 80-pin connector option is intended for use on drives that plug directly into backplane connector in the host
equipment. In such installations, all backplane wiring segments are subject to the electromagnetic concepts
presented in SPI-4 Standard T10/1365D section 6. For LC model drives, installations with connectors on
cables are not recommended.
9.6.4
Mating connectors
Part numbers for the different type connectors that mate with the various Cheetah 15K.3 SCSI I/O connectors
are given in the sections following.
9.6.4.1
Mating connectors for LW model drives
The nonshielded cable connector shall be a 68 conductor connector consisting of two rows of 34 male contacts
with adjacent contacts 0.050 inch (1.27 mm) apart.
Maximum transfer rate
Asynchronous
Fast-5
yes
yes
yes
yes
Cheetah 15K.3 SCSI Product Manual, Rev. G
Fast-20
Fast-40
Fast-10
(Ultra)
(Ultra2)
yes
yes
yes
yes
yes
Fast-80
Fast-160
(Ultra160)
(Ultra320)
no
no
yes
no
yes
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