NSC DS78LS120W-883, DS78LS120J-883 Datasheet
September 1999
DS78LS120
Dual Differential Line Receiver (Noise Filtering and
Fail-Safe)
General Description
The DS78LS120 is a high performance, dual differential,TTL
compatible line receiver for both balanced and unbalanced
digital data transmission. The inputs are compatible with
EIA, Federal and MIL standards.
The line receiver will discriminate a
over a common-mode range of
over a range of
Circuit features include hysteresis and response control for
applications where controlled rise and fall times and/or high
frequency noise rejection are desirable. Threshold offset
control is provided for fail-safe detection, should the input be
open or short. Each receiver includes an optional 180Ω terminating resistor and the output gate contains a logic strobe
for time discrimination. The DS78LS120 is specified over a
−55˚C to +125˚C temperature range.
±
15V.
±
200 mV input signal
±
10V and a±300 mV signal
Connection Diagram
Input specifications meet or exceed those of the popular
DS7820 line receiver.
Features
n Meets EIA standards RS232-C, RS422 and RS423,
Federal Standards 1020, 1030 and MIL-188-114
n Input voltage range of
common-mode)
n Separate strobe input for each receiver
n 5k typical input impedance
n Optional 180Ω termination resistor
n 50mV input hysteresis
n 200mV input threshold
n Separate fail-safe mode
±
15V (differential or
DS78LS120 Dual Differential Line Receiver (Noise Filtering and Fail-Safe)
Dual-In-Line-Package
DS007499-1
Top View
Order Number DS78LS120J/883 or DS78LS120W/883
See NS Package Number J16A or W16A
see RETS Data Sheet.
© 1999 National Semiconductor Corporation DS007499 www.national.com
Absolute Maximum Ratings (Note 2)
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.
Supply Voltage 7V
Input Voltage
Strobe Voltage 7V
Output Sink Current 50 mA
Storage Temperature Range −65˚C to +150˚C
±
25V
Maximum Power Dissipation at 25˚C
(Note 1) 1433 mV
Lead Temperature (Soldering, 4 sec) 260˚C
Operating Conditions
Supply Voltage (V
Temperature (T
) 4.5 5.5 V
CC
) −55 +125 ˚C
A
Common-Mode Voltage (V
Min Max Units
) −15 +15 V
CM
Electrical Characteristics (Notes 3, 4)
Symbol Parameter Conditions Min Typ Max Units
V
V
V
V
R
R
R
I
V
Differential Threshold Voltage I
TH
Differential Threshold Voltage I
TL
Differential Threshold Voltage I
TH
with Fail-Safe Offset=5V I
TL
Input Resistance −15V ≤ VCM≤ 15V, 0V ≤ VCC≤ 7V 4 5 kΩ
IN
Line Termination Resistance T
T
Offset Control Resistance T
O
Data Input Current (Unterminated) V
IND
Input Balance I
THB
(Note 6) R
V
V
I
I
I
V
V
I
Logical “1” Output Voltage I
OH
Logical “0” Output Voltage I
OL
Power Supply Current V
CC
Logical “1” Strobe Input Current V
IN (1)
Logical “0” Strobe Input Current V
IN (0)
Logical “1” Strobe Input Voltage VOL≤ 0.5, I
IH
Logical “0” Strobe Input Voltage VOH≥ 2.5V, I
IL
Output Short-Circuit Current V
OS
Note 1: Derate cavity package 9.6 mW/˚C above 25˚C.
Note 2: “Absolute Maximum Ratings”are those values beyond which the safety of the device cannot be guaranteed. Except for “Operating TemperatureRange” they
are not meant to imply that the devices should be operated at these limits. The table of “Electrical Characteristics” provides conditions for actual device operation.
Note 3: Unless otherwise specified min/max limits apply across the −55˚C to +125˚C temperature range for the DS78LS120. All typical values are for T
=
5V and V
Note 4: All currents into device pins shown as positive, out of device pins as negative, all voltages referenced to ground unless otherwise noted. All values shown
as max or min on absolute value basis.
Note 5: Only one output at a time should be shorted.
Note 6: Refer to EIA-RS422 for exact conditions.
=
0V.
CM
=
−400 µA, V
OUT
=
4 mA, V
OUT
=
−400 µA, V
OUT
=
4 mA, V
OUT
=
25˚C 100 180 300 Ω
A
=
25˚C 42 56 70 kΩ
A
=
10V 2 3.1 mA
CM
=
V
0V 0V ≤ V
CM
=
V
−10V −2 −3.1 mA
CM
=
−400 µA, V
OUT
=
500Ω
S
=
I
4 mA, V
OUT
=
R
500Ω
S
=
−400 µA, V
OUT
=
4 mA, V
OUT
=
5.5V V
CC
=
V
−0.5V, (Both Receivers) V
DIFF
=
=
=
0V, V
5.5V, V
0V, V
OUT
OUT
STROBE
STROBE
OUT
≥ 2.5V −7V ≤ VCM≤ 7V 0.06 0.2 V
OUT
≤ 0.5V −7V ≤ VCM≤7V −0.08 −0.2 V
OUT
≥ 2.5V −7V ≤ VCM≤ 7V 0.47 0.7 V
OUT
≤ 0.5V −7V ≤ VCM≤ 7V −0.2 −0.42 V
OUT
≥ 2.5V, −7V ≤ VCM7V 0.1 0.4 V
OUT
≤ 0.5V, −7V ≤ VCM≤ 7V −0.1 −0.4 V
OUT
=
1V, V
DIFF
=
−1V, V
DIFF
=
3V 1 100 µA
DIFF
=
−3V −290 −400 µA
DIFF
=
4mA 2.0 1.12 V
−15 ≤ V
−15V ≤ V
15V
=
4.5V 2.5 3 V
CC
=
4.5V 0.35 0.5 V
CC
CM
CM
≤15V 0.06 0.3 V
CM
≤
CM
≤ 7V 0 −0.5 mA
CC
=
15V 10 16 mA
=
−15V 10 16 mA
−0.08 −0.3 V
,=−400 µA 1.12 0.8 V
=
5.5V, V
CC
STROBE
=
0V,(Note 5) −30 −100 −170 mA
A
=
25˚C, V
CC
Switching Characteristics
=
V
CC
Symbol Parameter Conditions Min Typ Max Units
t
pd0(D)
t
pd1(D)
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=
5V, T
25˚C
A
Differential Input to “0” Output 38 60 ns
Differential Input to “1” Output Response Pin Open, C
=
L
15 pF, R
=
2kΩ 38 60 ns
L
Switching Characteristics (Continued)
=
V
CC
Symbol Parameter Conditions Min Typ Max Units
t
pd0(S)
t
pd1(S)
=
5V, T
25˚C
A
Strobe Input to “0” Output 16 25 ns
Strobe Input to “1” Output 12 25 ns
AC Test Circuit and Switching Time Waveforms
Differential and Strobe Input Signal
Includes probe and test fixture capacitance
Note: Optimum switching response is obtained by minimizing stray capacitance on Response Control pin (no external connection).
DS007499-3
DS007499-4
Application Hints
Balanced Data Transmission
DS007499-5
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