Electrical Interface; Figure 2. Single-Ended Transmitter And Receiver - Seagate MEDALIST 1080SL Product Manual

16 Medalist 1080sl SCSI Product Manual, August 1995
Always rest the drive on a padded, antistatic surface until you mount
it in the host system.
Do not touch the connector pins or the printed circuit board.
Do not remove the factory-installed labels from the drive or cover them
with additional labels. If you do, you void the warranty. Some factory-
installed labels contain information needed to service the drive. Others
are used to seal out dirt and contamination.

2.3 Electrical interface

The ST51080N drive is designed to use singled-ended interface signals.
They employ singled-ended drivers and receivers and active terminator
circuitry. Figure 2 shows a single-ended transmitter and receiver without
the active terminator circuitry.
Transmitter characteristics. The drive uses an ANSI SCSI-compat-
ible, 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 volts.
Receiver characteristics. The drive uses an ANSI SCSI single-
ended receiver with hysteresis gate or equivalent as a line receiver.
The loss in the cable is defined as the difference between the voltages
of the input and output signals, as shown below:
Logic level Driver output (x)
Asserted (1)
0.0V
Negated (0)
2.5V
+2.85V
Line driver
(transmitter or transceiver)
110
ohms
ANSI SCSI
compatible circuit

Figure 2. Single-ended transmitter and receiver

Receiver input (x)
x 0.4V 0.0V x
x 5.25V 2.0V x
+2.85V
110
ohms
Flat cable pair
0.8V
5.25V
Line receiver
ANSI SCSI
compatible
circuit