SN75177B, SN75178B
DIFFERENTIAL BUS REPEATERS
SLLS002C – D2606, JULY 1985 – REVISED FEBRUAR Y 1993
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
Copyright 1993, Texas Instruments Incorporated
2–1
• 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
description
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
ENABLE OUTPUTS
A – B EN T Y Z
VID ≥ 0.2 V H H H L
–0.2 V < VID < 0.2 V H ? ??
V
ID
≤ 0.2 V H L LH
X L ZZZ
SN75178B
DIFFERENTIAL INPUTS
ENABLE OUTPUTS
A – B EN T Y Z
VID ≥ 0.2 V L H H L
–0.2 V < VID < 0.2 V L ? ??
V
ID
≤ 0.2 V L L LH
X H ZZZ
H = high level, L = low level, ? = indeterminate, X = irrelevant, Z = impedance (off)
1
2
3
4
8
7
6
5
V
CC
T
EN
GND
A
B
Z
Y
SN75177B ...D OR P PACKAGE
(TOP VIEW)
1
2
3
4
8
7
6
5
V
CC
T
EN
GND
A
B
Z
Y
SN75178B ...P PACKAGE
(TOP VIEW)
THE SN75177B IS NOT
RECOMMENDED FOR NEW DESIGN
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.
SN75177B, SN75178B
DIFFERENTIAL BUS REPEATERS
SLLS002C – D2606, JULY 1985 – REVISED FEBRUARY 1993
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
2–2
logic symbols
†
logic diagrams (positive logic)
SN75178B
EN
5
6
3
8
7
2
EN
A
B
T
Y
Z
SN75177B
Z
Y
T
B
A
EN
2
7
8
3
6
5
EN
SN75178B
SN75177B
Receiver Driver
5
6
Y
Z
3
8
7
2
EN
A
B
T
T
B
A
EN
2
7
8
3
Z
Y
6
5
DriverReceiver
†
These symbols are in accordance with ANSI/IEEE Std 91-1984 and
IEC Publication 617-12.
schematics of inputs and outputs
960 Ω
NOM
GND
Output
V
CC
TYPICAL OF ALL DRIVER OUTPUTS
16.8 kΩ
NOM
Input
V
CC
EQUIVALENT OF EACH RECEIVER INPUT
Enable inputs: Req = 8 kΩ NOM
Driver input: Req = 3 kΩ NOM
Input
R
eq
V
CC
EQUIVALENT OF EACH INPUT
Output
85 Ω
NOM
V
CC
TYPICAL OF RECEIVER OUTPUT
960 Ω
NOM
SN75177B, SN75178B
DIFFERENTIAL BUS REPEATERS
SLLS002C – D2606, JULY 1985 – REVISED FEBRUARY 1993
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
2–3
absolute maximum ratings over operating free-air temperature range (unless otherwise noted)
Supply voltage, VCC (see Note 1) 7 V. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Voltage range at any bus terminal –10 V to 15 V. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Differential input voltage (see Note 2) ±25 V. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Enable input voltage 5.5 V. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Continuous total dissipation See Dissipation Rating Table. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Operating free-air temperature range 0°C to 70°C. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Storage temperature range –65°C to 150°C. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Lead temperature 1,6 mm (1/16 inch) from case for 10 seconds 260°C. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
NOTES: 1. All voltage values, except differential input voltage, are with respect to network ground terminal.
2. Differential input voltage is measured at the noninverting input with respect to the corresponding inverting input.
DISSIPATION RATING TABLE
PACKAGE
TA ≤ 25°C
POWER RATING
DERATING FACTOR
ABOVE TA = 25°C
TA = 70°C
POWER RATING
D 725 mW 5.8 mW/°C 464 mW
P 1000 mW 8.0 mW/°C 640 mW
recommended operating conditions
MIN NOM MAX UNIT
Supply voltage, V
CC
4.75 5 5.25 V
High-level input voltage, V
IH
EN or EN 2 V
low-level input voltage, V
IL
EN or EN 0.8 V
Common-mode input voltage, V
IC
–7
†
12 V
Differential input voltage, V
ID
±12 V
p
Driver –60 mA
High-level output current, I
OH
Receiver –400 µA
p
Driver 60
Low-level output current, I
OL
Receiver 8
mA
Operating free-air temperature, T
A
0 70 °C
†
The algebraic convention, where the less-positive (more-negative) limit is designated minimum, is used in this data sheet for common-mode input
voltage and threshold voltage.
SN75177B, SN75178B
DIFFERENTIAL BUS REPEATERS
SLLS002C – D2606, JULY 1985 – REVISED FEBRUARY 1993
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
2–4
DRIVER SECTION
electrical characteristics over recommended ranges of supply voltage and operating free-air
temperature (unless otherwise noted)
PARAMETER TEST CONDITIONS MIN TYP†MAX UNIT
V
IK
Input clamp voltage II = –18 mA –1.5 V
V
O
Output voltage IO = 0 0 6 V
|V
OD1
| Differential output voltage IO = 0 1.5 6 V
1/2 V
OD1
|V
OD2
| Differential output voltage
R
L
=
100 Ω
,
See Figure 1
OD1
or 2
§
V
RL = 54 Ω, See Figure 1 1.5 2.5 5
|V
OD3
| Differential output voltage See Note 3 1.5 5 V
Change in magnitude of
∆|V
OD|
gg
diferential output voltage
‡
±0.2
VpR
L
=
54 Ω
or
100 Ω
,See Figure
1
3
VOCCommon-mode output voltage
–1
V
Change in magnitude of
∆|VOC|
gg
common-mode output voltage
‡
±0.2
V
I
O
Output current VCC = 0, VO = –7 V to 12 V ±100 µA
I
OZ
High-impedance-state output current VO = –7 V to 12 V ±100 µA
I
IH
High-level input current VI = 2.4 V 20 µA
I
IL
Low-level input current VI = 0.4 V –400 µA
VO = –7 V –250
I
OS
Short-circuit output current
VO = V
CC
250
mA
VO = 12 V 250
pp
p
Outputs enabled 57 70
ICCSupply current (total package)
No load
Outputs disabled 26 35
mA
†
All typical values are at VCC = 5 V and TA = 25°C.
‡
∆|VOD| and ∆|VOC| are the changes in magnitude of VOD and VOC, respectively, that occur when the input is changed from a high level to a low
level.
§
The minimum V
OD2
with a 100-Ω load is either 1/2 V
OD1
or 2, whichever is greater.
NOTE 3: See Figure 3.5 of EIA Standard RS-485.
switching characteristics, VCC = 5 V, TA = 25°C
PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
t
dD
Differential-output delay time
15 20 ns
t
tD
Differential-output transition time
R
L
= 54 Ω,
See
Fig
u
re
3
20 30 ns
t
PZH
Output enable time to high level RL = 110 Ω, See Figure 4 85 120 ns
t
PZL
Output enable time to low level RL = 110 Ω, See Figure 5 40 60 ns
t
PHZ
Output disable time from high level RL = 110 Ω, See Figure 4 150 250 ns
t
PLZ
Output disable time from low level RL = 110 Ω, See Figure 5 20 30 ns
SN75177B, SN75178B
DIFFERENTIAL BUS REPEATERS
SLLS002C – D2606, JULY 1985 – REVISED FEBRUARY 1993
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
2–5
SYMBOL EQUIVALENTS
DATA SHEET PARAMETER
RS-422-A RS-485
V
O
V
oa, Vob
V
oa, Vob
|V
OD1
| V
o
V
o
|V
OD2
| Vt (RL = 100 Ω) Vt (RL = 54 Ω)
|V
OD3
|
Vt (Test Termination)
Measurement 2)
∆|VOD| | |Vt| – |Vt|| | |Vt| – |Vt||
V
OC
|VOS| |VOS|
∆|VOC| |VOS – VOS| |VOS – VOS|
I
OS
|Isa|,|Isb|
I
O
|Ixa|,|Ixb| Iia,I
ib
RECEIVER SECTION
electrical characteristics over recommended ranges of common-mode input voltage, supply
voltage, and operating free-air temperature (unless otherwise noted)
PARAMETER TEST CONDITIONS MIN TYP†MAX UNIT
V
T+
Positive-going input threshold voltage VO = 2.7 V, IO = –0.4 mA 0.2 V
V
T–
Negative-going input threshold voltage VO = 0.5 V, IO = 8 mA –0.2
‡
V
V
hys
Input hysteresis (VT+ – VT–) 50 mV
V
IK
Input clamp voltage at EN II = –18 mA –1.5 V
V
OH
High-level output voltage
VID = 200 mV ,
See Figure 2
IOH = –400 µA,
2.7 V
V
OL
Low-level output voltage
VID = –200 mV,
See Figure 2
IOL = 8 mA,
0.45 V
p
p
20
IOZHigh-impedance-state output current
V
O
= 0.4 V to 2.4
V
–400
µ
A
p
Other input at 0 V ,
VI = 12 V 1
IILine input current
See Note 4
VI = –7 V –0.8
mA
I
IH
High-level enable-input current VIH = 2.7 V 20 µA
I
IL
Low-level enable-input current VIL = 0.4 V –200 µA
r
i
Input resistance 12 kΩ
I
OS
Short-circuit output current –15 –85 mA
pp
p
Outputs enabled 57 70
ICCSu ly current (total ackage)
No load
Outputs disabled 26 35
mA
†
All typical values are at VCC = 5 V, TA = 25°C.
‡
The algebraic convention, where the less-positive (more-negative) limit is designated minimum, is used in this data sheet for common-mode input
voltage and threshold voltage levels only.
NOTE 4: Refer to EIA Standard RS-422 for exact conditions.
switching characteristics, VCC = 5 V, TA = 25°C
PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
t
PLH
Propagation delay time, low-to-high level output
V
= –1.5 V to 1.5 V,
19 35
t
PHL
Propagation delay time, high-to-low level output
ID
,
CL = 15 pF, See Figure 6
30 40
ns
t
PZH
Output enable time to high level
p
10 20
t
PZL
Output enable time to high level
C
L
= 15 pF,
See Figure 7
12 20
ns
t
PHZ
Output disable time from high level
p
25 35
t
PLZ
Output disable time from low level
C
L
= 15 pF,
See Figure 8
17 25
ns
SN75177B, SN75178B
DIFFERENTIAL BUS REPEATERS
SLLS002C – D2606, JULY 1985 – REVISED FEBRUARY 1993
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
2–6
PARAMETER MEASUREMENT INFORMATION
V
OC
2
R
L
2
R
L
V
OD2
V
OL
V
OH
–I
OH
+I
OL
V
ID
Figure 1. Driver VOD and VOC Figure 2. Receiver VOH and V
OL
VOLTAGE WAVEFORMS
50%
t
tD
t
dD
1.5 V
10%
t
tD
≈ 2.5 V
≈ – 2.5 V
90%
50%
Output
t
dD
0 V
3 V
1.5 V
Input
TEST CIRCUIT
Output
(see Note B)
CL = 50 pF
RL = 54 Ω
50 Ω
Generator
(see Note A)
Figure 3. Driver Differential-Output Test Circuit and Voltage Waveforms
VOLTAGE WAVEFORMS
t
PHZ
1.5 V
2.3 V
0.5 V
0 V
3 V
t
PZH
Output
Input
1.5 V
S1
0 V or 3 V
Output
(see Note B)
CL = 50 pF
TEST CIRCUIT
50 Ω
V
OH
V
off
≈ 0
V
ÁÁÁÁ
(SN75178B)
(SN75177B)
SN75178B
Enable is
Active Low
RL = 110 Ω
Generator
(see Note A)
Figure 4. Driver Enable and Disable Times
VOLTAGE WAVEFORMS
5 V
V
OL
0.5 V
t
PZL
3 V
0 V
t
PLZ
1.5 V
2.3 V
1.5 V
Output
Input
TEST CIRCUIT
Output
RL = 110 Ω
5 V
S1
(see Note B)
CL = 50 pF
50 Ω
3 V or 0 V
(SN75178B)
ÁÁÁÁ
(SN75177B)
SN75178B
Enable is
Active Low
Generator
(see Note A)
Figure 5. Driver Enable and Disable Times
NOTES: A. The input pulse is supplied by a generator having the following characteristics: PRR ≤ 1 MHz, 50% duty cycle, tr ≤ 6 ns, tf ≤ 6 ns,
ZO = 50 Ω.
B. CL includes probe and jig capacitance.
SN75177B, SN75178B
DIFFERENTIAL BUS REPEATERS
SLLS002C – D2606, JULY 1985 – REVISED FEBRUARY 1993
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
2–7
PARAMETER MEASUREMENT INFORMATION
1.3 V
1.5 V
VOLTAGE WAVEFORMS
1.3 V
0 V
3 V
V
OL
V
OH
t
PHL
t
PLH
1.5 V
Output
Input
TEST CIRCUIT
(see Note B)
CL = 15 pF
Output
1.5 V
50 Ω
Generator
(see Note A)
Figure 6. Receiver Propagation Delay Times
V
OH
0.5 V
≈ 1.3 V
t
PHZ
1.5 V
0 V
3 V
S1 to 1.5 V
S2 Closed
S3 Closed
t
PLZ
≈ 1.3 V
V
OL
0.5 V
1.5 V
0 V
S1 to –1.5 V
S2 Closed
S3 Closed
3 V
≈ 4.5 V
V
OL
1.5 V
0 V
1.5 V
3 V
t
PZL
0 V
1.5 V
V
OH
0 V
Output
Input
t
PZH
S1 to 1.5 V
S2 Open
S3 Closed
1.5 V
3 V
TEST CIRCUIT
(see Note B)
CL = 15 pF
50 Ω
S3
5 V
S2
2 kΩ
5 kΩ
S1
–1.5 V
1.5 V
VOLTAGE WAVEFORMS
(see Note C)
Output
Output
Input
Output
Input
Output
Input
(SN75178B)
(SN75177B)
(SN75178B)
(SN75177B)
(SN75178B)
(SN75177B)
(SN75178B)
(SN75177B)
S1 to –1.5 V
S2 Closed
S3 Open
Generator
(see Note A)
Figure 7. Receiver Output Enable and Disable Times
NOTES: A. The input pulse is supplied by a generator having the following characteristics: PRR ≤ 1 MHz, 50% duty cycle, tr ≤ 6 ns, tf ≤ 6 ns,
ZO = 50 Ω.
B. CL includes probe and jig capacitance.
C. All diodes are 1N916 or equivalent.
SN75177B, SN75178B
DIFFERENTIAL BUS REPEATERS
SLLS002C – D2606, JULY 1985 – REVISED FEBRUARY 1993
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
2–8
TYPICAL CHARACTERISTICS
– High-Level Output Voltage – V
DRIVER HIGH-LEVEL OUTPUT VOLTAGE
vs
HIGH-LEVEL OUTPUT CURRENT
TA = 25°C
VCC = 5 V
4.5
4
3.5
3
2.5
2
1.5
1
0.5
–100–80–60–40–20
0
–120
5
IOH – High-Level Output Current – mA
0
DRIVER LOW-LEVEL OUTPUT VOLTAGE
vs
LOW-LEVEL OUTPUT CURRENT
VCC = 5 V
TA = 25°C
IOH – Low-Level Output Current – mA
0 12020 40 60 80 100
5
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
V
OH
– High-Level Output Voltage – V
V
OH
Figure 8 Figure 9
100
– Differential Output Voltage – V
DRIVER DIFFERENTIAL OUTPUT VOLTAGE
vs
DRIVER OUTPUT CURRENT
VCC = 5 V
TA = 25°C
3.5
3
2.5
2
1.5
1
0.5
908070605040302010
0
4
IO – Output Current – mA
0
VO – Output Voltage – V
VID – Differential Input Voltage – mV
2
1
0
–125 –75 –25 0 25
3
4
5
50 75 100 125
RECEIVER OUTPUT VOLTAGE
vs
DIFFERENTIAL INPUT VOLTAGE
TA = 25°CIO = 0VCC = 5 V
V
T–
V
T+
VIC =
12 V
V
T–
V
T+
V
O
OD
V
V
T–
V
T+
VIC =
0 V
VIC =
–12 V
–100 –50
Figure 10 Figure 11
SN75177B, SN75178B
DIFFERENTIAL BUS REPEATERS
SLLS002C – D2606, JULY 1985 – REVISED FEBRUARY 1993
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
2–9
TYPICAL CHARACTERISTICS
– High-Level Output Voltage – V
RECEIVER HIGH-LEVEL OUTPUT VOLTAGE
vs
HIGH-LEVEL OUTPUT CURRENT
VCC = 5.25 V
VCC = 5 V
VCC = 4.75 V
0 –10 –20 –30 –40 –50
5
0
1
2
3
4
IOH – High-Level Output Current – mA
RECEIVER HIGH-LEVEL OUTPUT VOLTAGE
vs
FREE-AIR TEMPERATURE
IOH = –440 µA
VID = 200 mV
4
3
2
1
70605040302010
0
80
5
TA – Free-Air Temperature – °C
0
V
OH
VCC = 5 V
– High-Level Output Voltage – V
V
OH
TA = 25°C
VID = 0.2 V
Figure 12 Figure 13
– Low-Level Output Voltage – V
RECEIVER LOW-LEVEL OUTPUT VOLTAGE
vs
LOW-LEVEL OUTPUT CURRENT
TA = 25°C
VCC = 5 V
0.5
0.4
0.3
0.2
0.1
252015105
0
30
0.6
IOL – Low-Level Output Current – mA
0
RECEIVER LOW-LEVEL OUTPUT VOLTAGE
vs
FREE-AIR TEMPERATURE
IOL = 8 mA
VID = –200 mV
VCC = 5 V
TA – Free-Air Temperature – °C
0.6
0
0.1
0.2
0.3
0.4
0.5
100806040200–20 120–40
V
OL
– Low-Level Output Voltage – V
V
OL
Figure 14 Figure 15
SN75177B, SN75178B
DIFFERENTIAL BUS REPEATERS
SLLS002C – D2606, JULY 1985 – REVISED FEBRUARY 1993
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
2–10
APPLICATION INFORMATION
SN75176B
R
T
R
T
R
T
R
T
SN75177B
SN75178B
SN75176B
SN75176B
1/2 SN75179B
R
T
R
T
Direction
Control
1/2 SN75179B
NOTE: The line should be terminated at both ends in its characteristic impedance. Stub lengths off the main line should be kept as short as
possible.
Figure 16. Typical Application Circuit
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product or service without notice, and advises its customers to obtain the latest version of relevant information
to verify, before placing orders, that the information being relied on is current and complete.
TI warrants performance of its semiconductor products and related software to the specifications applicable at
the time of sale in accordance with TI’s standard warranty. Testing and other quality control techniques are
utilized to the extent TI deems necessary to support this warranty. Specific testing of all parameters of each
device is not necessarily performed, except those mandated by government requirements.
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severe property or environmental damage (“Critical Applications”).
TI SEMICONDUCTOR PRODUCTS ARE NOT DESIGNED, INTENDED, AUTHORIZED, OR WARRANTED
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Copyright 1998, Texas Instruments Incorporated
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