DS55107 Datasheet, PDF (6/10 Pages) National Semiconductor (TI) – Dual Line Receivers

Typical Applications (Continued)
swing is symmetrical about it for maximum noise margin
The reference voltage should be in the range of b3 0V to
a3 0V It can be provided by a voltage supply or by a volt-
age divider from an available supply voltage
Unbalanced or Single-Line Systems
DS75108 Wired-OR Output Connections
TL F 9446–4
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 DS55107 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 b3 0V and a3 0V
preferably at ground Failure to do so will cause improper
operation of the unit being used because of common bias
circuitry for the current sources of the two receivers
The DS55107 DS75107 and DS75108 line receivers fea-
ture a common mode input voltage range of g3 0V This
satisfies the requirements for all but the noisiest system ap-
plications For these severe noise environments the com-
mon mode range can be extended by the use of external
input attenuators Common mode input voltages can in this
way be reduced to g3 0V at the receiver input terminals
Differential data signals will be reduced proportionately In-
put sensitivity input impedance and delay times will be ad-
versely affected
The DS75108 line receivers feature an open-collector-out-
put circuit that can be connected in the DOT-OR logic con-
figuration with other DS75108 outputs This allows a level of
logic to be implemented without addtional logic delay
Increasing Common Mode Input
Voltage Range of Receiver
TL F 9446 – 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
Standard Devices
TL F 9446 – 7
TL F 9446–5
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TL F 9446 – 8