DS75154 Quad Line Receiver
May 1998
DS75154
Quad Line Receiver
General Description
The DS75154 is a quad monolithic line receiver designed to
satisfy the requirements of the standard interface between
data terminal equipment and data communication equipment
as defined by EIA Standard RS-232C. Other applications are
in relatively short, single-line, point-to-point data transmis-
sion systems and for level translators. Operation is normally
from a single 5V supply; however, a built-in option allows op-
eration from a 12V supply without the use of additional com-
ponents. The output is compatible with most TTL and LS cir-
cuits when either supply voltage is used.
In normal operation, the threshold-control terminals are con-
nected to the V
CC1
terminal, pin 15, even if power is being
supplied via the alternate V
CC2
terminal, pin 16. This pro-
vides a wide hysteresis loop which is the difference between
the positive-going and negative-going threshold voltages. In
this mode, if the input voltage goes to zero, the output volt-
age will remain at the low or high level as determined by the
previous input.
For fail-safe operation, the threshold-control terminals are
open. This reduces the hysteresis loop by causing the
negative-going threshold voltage to be above zero. The
positive-going threshold voltage remains above zero as it is
unaffected by the disposition of the threshold terminals. In
the fail-safe mode, if the input voltage goes to zero or an
open-circuit condition, the output will go to the high level re-
gardless of the previous input condition.
Features
n
Input resistance, 3 k鈩?to 7 k鈩?over full RS-232C voltage
range
n
Input threshold adjustable to meet 鈥渇ail-safe鈥?/div>
requirements without using external components
n
Inverting output compatible with TTL or LS
n
Built-in hysteresis for increased noise immunity
n
Output with active pull-up for symmetrical switching
speeds
n
Standard supply voltage 鈥?5V or 12V
Schematic Diagram
DS005795-1
Note:
When using V
CC1
(pin 15), V
CC2
(pin 16) may be left open or shorted to V
CC1
. When using V
CC2
, V
CC1
must be left open or connected to the
threshold control pins.
漏 1998 National Semiconductor Corporation
DS005795
www.national.com
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