SN75177B, SN75178B
DIFFERENTIAL BUS REPEATERS
SLLS002C – D2606, JULY 1985 – REVISED FEBRUARY 1993
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Meets EIA Standards RS-422-A and RS-485
and CCITT Recommendations V.11 and X.27
Designed for Multipoint Transmission on
Long Bus Lines in Noisy Environments
3-State Outputs
Bus Voltage Range . . . – 7 V to 12 V
Positive and Negative Current Limiting
Driver Output Capability . . . 60 mA Max
Driver Thermal Shutdown Protection
Receiver Input Impedance . . . 12 kΩ Min
Receiver Input Sensitivity . . .
±
200 mV
Receiver Input Hysteresis . . . 50 mV Typ
Operates From Single 5-V Supply
Low Power Requirements
SN75177B . . . D OR P PACKAGE
(TOP VIEW)
V
CC
T
EN
GND
1
2
3
4
8
7
6
5
A
B
Z
Y
SN75178B . . . P PACKAGE
(TOP VIEW)
V
CC
T
EN
GND
1
2
3
4
8
7
6
5
A
B
Z
Y
description
THE SN75177B IS NOT
RECOMMENDED FOR NEW DESIGN
The SN75177B and SN75178B differential bus repeaters are monolithic integrated devices each designed for
one-way data communication on multipoint bus transmission lines. These devices are designed for balanced
transmission bus line applications and meet EIA Standard RS-422-A and RS-485 and CCITT
Recommendations V.11 and X.27. Each device is designed to improve the performance of the data
communication over long bus lines. The SN75177B and SN75178B are identical except for the complementary
enable inputs, which allow the devices to be used in pairs for bidirectional communication.
The SN75177B and SN75178B feature positive- and negative-current limiting 3-state outputs for the receiver
and driver. The receiver features high input impedance, input hysteresis for increased noise immunity, and input
sensitivity of
±
200 mV over a common-mode input voltage range of – 7 V to 12 V. The driver features thermal
shutdown for protection from line fault conditions. Thermal shutdown is designed to occur at a junction
temperature of approximately 150°C. The driver is designed to drive current loads up to 60 mA maximum.
The SN75177B and SN75178B are designed for optimum performance when used on transmission buses
employing the SN75172 and SN75174 differential line drivers, SN75173 and SN75175 differential line
receivers, or SN75176B bus transceiver.
Function Tables
SN75177B
DIFFERENTIAL INPUTS
A–B
VID
≥
0.2 V
– 0.2 V
<
VID
<
0.2 V
VID
≤
0.2 V
X
ENABLE
EN
H
H
H
L
SN75178B
DIFFERENTIAL INPUTS
A–B
VID
≥
0.2 V
– 0.2 V
<
VID
<
0.2 V
VID
≤
0.2 V
X
ENABLE
EN
L
L
L
H
T
H
?
L
Z
OUTPUTS
Y
H
?
L
Z
Z
L
?
H
Z
T
H
?
L
Z
OUTPUTS
Y
H
?
L
Z
Z
L
?
H
Z
H = high level, L = low level, ? = indeterminate, X = irrelevant, Z = impedance (off)
Copyright
©
1993, Texas Instruments Incorporated
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of Texas Instruments
standard warranty. Production processing does not necessarily include
testing of all parameters.
POST OFFICE BOX 655303
•
DALLAS, TEXAS 75265
2–1
TI [ TEXAS INSTRUMENTS ]
