Seagate CHEETAH ST373207LW/LC - Manual (Page 93)

Cheetah 10K.7 SCSI Product Manual, Rev. D 83
9.8 Terminator requirements
Caution: These drives do not have onboard internal terminators. The user, systems integrator or host equip-
ment manufacturer must provide a terminator arrangement external to the drive when termination is
required. For LW drives, terminator modules can be purchased that plug between the SCSI I/O
cable and the drive I/O connector or on the end of a short I/O cable stub extending past the last
cable connector. LC drives are designed to be plugged into a backpanel connector without cabling.
9.9 Terminator power
LW drives
You can configure terminator power from the drive to the SCSI bus or have the host adaptor or other device
supply terminator power to the external terminator. See Section 8.1 for illustrations that show how to place
jumpers for this configuration.
LC drives
These drives cannot furnish terminator power because no conductors in the 80-pin I/O connector are devoted
to terminator power.
Table 20: Example Twist-n-flat cables - into a multi-drive backplane
Cable
description
Differential
impedance,
nominal
Single-
ended
impedance,
nominal Single-
ended
capacitance,
maximum
Time
delay,
nominal
Conductor
DC
resistance,
nominal
Maximum twist-n-flat
cable length
U320
transfer rate U160
transfer rate
TPE, 22.25” twist,
1.75” flat, (24” flat
to flat), 30 AWG
solid tinned copper 131 ohms 93 ohms 15.3 pF/ft 1.45 ns/ft 0.105
ohms/ft
3.05 meters
(10.0 ft) 6.1 meters
(20.0 ft)
TPE, 8.1” twist,
1.75” flat, (9.85” flat
to flat), 30 AWG
solid tinned copper 131 ohms 93 ohms 15.3 pF/ft 1.45 ns/ft 0.105
ohms/ft
2.45 meters
(8.33 ft) 4.9 meters
(16.66 ft)
TPE, 4.25” twist,
1.75” flat, (6” flat to
flat), 30 AWG solid
tinned copper 131 ohms 93 ohms 15.3 pF/ft 1.45 ns/ft 0.105
ohms/ft
1.52 meters
(5.0 ft) 3.04 meters
(10.0 ft)