DS75107 Datasheet, PDF (5/9 Pages) National Semiconductor (TI) – Dual Line Receiver

Typical Applications (Continued)
The strobe feature of the receiver and the inhibit feature of
the driver allows the DS75107 dual line circuit to be used in
data-bus or party-line systems. In these applications, several
drivers and receivers may share a common transmission
line. An enabled driver transmits data to all enabled receiv-
ers on the line while other drivers and receivers are disabled.
Data is thus time multiplexed on the transmission line.
DS75107 device specifications allow widely varying thermal
and electrical environments at the various driver and re-
ceiver locations. The data-bus system offers maximum per-
formance at minimum cost.
The DS75107 dual line circuits may also be used in unbal-
anced or single line systems. Although these systems do not
offer the same performance as balanced systems for long
lines, they are adequate for very short lines where environ-
ment noise is not severe.
The receiver threshold level is established by applying a DC
reference voltage to one receiver input terminal. The signal
from the transmission line is applied to the remaining input.
The reference voltage should be optimized so that signal
swing is symmetrical about it for maximum noise margin.
The reference voltage should be in the range of −3.0V to
+3.0V. It can be provided by a voltage supply or by a voltage
divider from an available supply voltage.
Unbalanced or Single-Line Systems
DS009446-4
Precautions in the Use of DS1603, DS3603, DS55107,
DS75107, DS75108 and DS75208 Dual Line Receivers
The following precaution should be observed when using or
testing DS75107 line circuits.
When only one receiver in a package is being used, at least
one of the differential inputs of the unused receiver should
be terminated at some voltage between −3.0V and +3.0V,
preferably at ground. Failure to do so will cause improper op-
eration of the unit being used because of common bias cir-
cuitry for the current sources of the two receivers.
The DS75107 line receiver features a common mode input
voltage range of ±3.0V. This satisfies the requirements for all
but the noisiest system applications. For these severe noise
environments, the common mode range can be extended by
the use of external input attenuators. Common mode input
voltages can in this way be reduced to ±3.0V at the receiver
input terminals. Differential data signals will be reduced pro-
portionately. Input sensitivity, input impedance and delay
times will be adversely affected.
Increasing Common Mode Input
Voltage Range of Receiver
DS009446-5
DS75108 Wired-OR Output Connections
DS009446-6
Circuit Differences Between “A” and Standard Devices
The difference between the “A” and standard devices is
shown in the following schematics of the input stage.
“A” Devices
DS009446-7
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