NSC DS78C120MW8, DS78C120MD8 Datasheet

DS78C120
Dual CMOS Compatible Differential Line Receiver

General Description

The DS78C120 is a high performance, dual differential,
CMOS compatible line receiver for both balanced and unbal­anced digital data transmission. The inputs are compatible
with EIA, Federal and MIL standards.

Input specifications meet or exceed those of the popular
DS7820 line receiver.

The line receiver will discriminate a

±

200 mV input signal

over a common-mode range of

±

10V and a±300 mV signal

over a range of

±

15V.

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 a 180Ω terminating re­sistor and theoutputgatecontainsalogicstrobe for time dis­crimination. The DS78C120 is specified over a −55˚C to
+125˚C temperature range.

Features

n Full compatibility with EIA Standards RS232-C, RS422

and RS423, Federal Standards 1020, 1030 and
MIL-188-114

n Input voltage range of

±

15V (differential or

common-mode)

n Separate strobe input for each receiver
n 1/2 V

CC

strobe threshold for CMOS compatibility

n 5k typical input impedance
n 50 mV input hysteresis
n 200 mV input threshold
n Operation voltage range=4.5V to 15V
n Separate fail-safe mode

Connection Diagram

TRI-STATE®is a registered trademark of National Semiconductor Corporation.

Dual-In-Line Package

DS005801-1

Top View

For Complete Military Product Specifications,

refer to the appropriate SMD or MDS.

Order Number DS78C120J/883
See NS Package Number J16A

May 1999

DS78C120 Dual CMOS Compatible Differential Line Receiver

© 1999 National Semiconductor Corporation DS005801 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 18V
Input Voltage

±

25V
Strobe Voltage 18V
Output Sink Current 50 mA

Maximum Power Dissipation (Note 1) at 25˚C

Cavity Package 1433 mW
Molded Package 1362 mW

Storage Temperature Range −65˚C to +150˚C
Lead Temperature (Soldering, 4 seconds) 260˚C

Operating Conditions

Min Max Units

Supply Voltage (V

CC

) 4.5 15 V

Temperature (T

A

)

DS78C120 −55 +125 ˚C

Common-Mode Voltage (V

CM

) −15 +15 V

Note 1: Derate cavity package 9.6 mW/˚C; derate molded package

10.9 mW/˚C above 25˚C.

Electrical Characteristics (Notes 3, 4)

Symbol Parameter Conditions Min Typ Max Units

V

TH

Differential Threshold I

OUT

=

−200 µA, −7V ≤ V

CM

≤ 7V 0.06 0.2 V

Voltage V

OUT

≥ VCC− 1.2V −15V ≤ VCM≤ 15V 0.06 0.3 V

V

TL

Differential Threshold I

OUT

=

1.6 mA,V

OUT

≤ 0.5V −7V ≤ VCM≤ 7V −0.08 −0.2 V

Voltage −15V ≤ V

CM

≤ 15V −0.08 −0.3 V

V

TH

Differential Threshold I

OUT

=

−200 µA, −7V ≤ V

CM

≤ 7V 0.47 0.7 V

Voltage Fail-Safe V

OUT

≥ VCC− 1.2V

V

TL

Offset=5V I

OUT

=

1.6 mA,V

OUT

≤ 0.5V −7V ≤ VCM≤ 7V 0.2 0.42 V

R

IN

Input Resistance −15V ≤VCM≤ 15V, 0V ≤ VCC≤ 15V 4 5 kΩ

R

T

Line Termination
Resistance

T

A

=

25˚C 100 180 300 Ω

R

O

Offset Control Resistance T

A

=

25˚C 56 kΩ

I

IND

Data Input Current 0V ≤ VCC≤ 15V V

CM

=

10V 2 3.1 mA

(Unterminated) V

CM

=

0V 0 −0.5 mA

V

CM

=

−10V −2 −3.1 mA

V

THB

Input Balance I

OUT

=

200 µA, V

OUT

≥ −7V ≤ VCM≤ 7V 0.1 0.4 V

(Note 6) V

CC

− 1.2V, R

S

=

500Ω

I

OUT

=

1.6 mA,V

OUT

≤ 0.5V −7V ≤ VCM≤ 7V −0.1 −0.4 V

R

S

=

500Ω

V

OH

Logical “1” Output Voltage I

OUT

=

−200 µA, V

DIFF

=

1V V

CC

− 1.2 VCC− 0.75 V

V

OL

Logical “0” Output Voltage I

OUT

=

1.6 mA, V

DIFF

=

−1V 0.25 0.5 V

I

CC

Power Supply Current 15V ≤ VCM≤ −15V, V

CC

=

5.5V 8 15 mA

V

DIFF

=

−0.5V

(Both Receivers)

V

CC

=

15V 15 30 mA

I

IN(1)

Logical “1” Strobe Input
Current

V

STROBE

=

15V, V

DIFF

=

3V

15 100 µA

I

IN(0)

Logical “0” Strobe Input
Current

V

STROBE

=

0V, V

DIFF

=

−3V

−0.5 −100 µA

V

IH

Logical “1” Strobe Input VOL≤ 0.5V, I

OUT

=

1.6 mA V

CC

=

5V 3.5 2.5 V

Voltage V

CC

=

10V 8.0 5.0 V

V

CC

=

15V 12.5 7.5 V

V

IL

Logical “0” Strobe Input
Voltage

VOHVCC− 1.2V, V

CC

=

5V 2.5 1.5 V

I

OUT

=

−200 µA V

CC

=

10V 5.0 2.0 V

V

CC

=

15V 7.5 2.5 V

I

OS

Output Short-Circuit
Current

V

OUT

=

0V, V

CC

=

15V, V

STROBE

=

0V, (Note 5) −5 −20 −40 mA

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 DS78C120. All typical values for T

A

=

25˚C, V

CC

=

5V and V

CM

=

0V.

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Electrical Characteristics (Notes 3, 4) (Continued)

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.

Switching Characteristics

V

CC

=

5V, T

A

=

25˚C

Symbol Parameter Conditions Min Typ Max Units

t

pd0(D)

Differential Input to “0” Output C

L

=

50 pF 60 100 ns

t

pd1(D)

Differential Input to “1” Output C

L

=

50 pF 100 150 ns

t

pd0(S)

Strobe Input to “0” Output C

L

=

50 pF 30 70 ns

t

pd1(S)

Strobe Input to “1” Output C

L

=

50 pF 100 150 ns

AC Test Circuit and Switching Time Waveforms

Differential and Strobe Input Signal

DS005801-3

*Includes probe and test fixture capacitance

DS005801-4

t

r

=

t

f

≤ 10 ns
PRR=1 MHz
Note: Optimum switching response is obtained by minimizing stray capacitance on Response Control pin (no external connection).

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