Hawk 4XL Product Manual, Rev. A
59
9.7
Electrical description
“N” and “W” models use single-ended interface signals. These signals must be terminated with 110-ohm active
termination circuits at each end of the total cable. Single-ended circuits use open collector or three state driv-
ers. All of these models can be configured to provide the SCSI termination.
9.7.1
“Single-ended drivers/receivers
For “N” and “W” models which use single-ended drivers and receivers, typical circuits are shown in Figure 18.
Terminator circuits (Note [1]) are to be enabled only when the disc drive is first or last in the daisy chain.
Transmitter characteristics
Single-ended drives use an ANSI SCSI compatible open collector single-ended driver. This driver is capable of
sinking a current of 48 mA with a low level output voltage of 0.4 volt.
Receiver characteristics
Single-ended drives use an ANSI SCSI single-ended receiver with hysteresis gate or equivalent as a line
receiver.
Figure 18.
Single-ended transmitters and receivers
Notes.
[1]
Part of active terminator circuits. Non-removable LSI terminators, enabled in the drive with jumper plug TE
when it is first or last in the daisy chain. Interface signals levels and logical sense at the drive I/O connec-
tor are defined as follows:
The difference in the voltages between input and output signals is due to the losses in the cable.
[2]
ANSI SCSI compatible circuits.
[3]
Total interface cable length should not exceed that specified in Section 9.6.3.1.
[4]
Source of drive terminator power is an active circuit which has an input source voltage selected by jumper
plug TP. See Figure 11.
Logic level
Driver output
Receiver input
NEGATED (0)
>2.5 V: <5.25 V
>2.0 V: <5.25 V
ASSERTED (1)
<0.4 V: >0.0 V
<0.8 V: >0. 0 V
Transmitter
(or transceiver)
Line Driver
Flat
Cable
Pair
[3]
[2]
[4]
[1]
110
Ohm
[4]
[1]
110
Ohm
Receiver
Line Receiver
[2]
TP
TP
