SN75276
FAIL-SAFE DIFFERENTIAL BUS TRANSCEIVER
SLLS212B – SEPTEMBER 1995 – REVISED APRIL 1998
D
D
D
D
D
D
D
D
D
D
D
D
D
D
Bidirectional Transceiver With Fail-Safe
Receiver
Meets or Exceeds the Requirements of ITU
Recommendation V.11
Electrically Compatible With ANSI
Standards TIA/EIA-422-B and TIA/EIA-485-A
Designed for Multipoint Transmission on
Long Bus Lines in Noisy Environments
3-State Driver and Receiver Outputs
Individual Driver and Receiver Enables
Wide Positive and Negative Input/Output
Bus Voltage Ranges
Driver Output Capability . . .
±
60 mA Max
Thermal Shutdown Protection
Driver Positive and Negative Current
Limiting
Receiver Input Impedance . . . 12 kΩ Min
Receiver Input Sensitivity . . .
–
300 mV/0 mV
Operates From Single 5-V Supply
Pin-to-Pin Compatible With SN75176A
D OR P PACKAGE
(TOP VIEW)
R
RE
DE
D
1
2
3
4
8
7
6
5
V
CC
B
A
GND
description
The SN75276 differential bus transceiver is a monolithic, integrated circuit designed for bidirectional data
communication on multipoint bus transmission lines. It is designed for balanced transmission lines and is
electrically compatible with ANSI Standards TIA/EIA-422-B and TIA/EIA-485-A, and meets ITU
Recommendation V.11.
The fail-safe operation ensures a known level on the circuit output under bus fault conditions. The circuit
provides a high-level output under floating-line, idle-line, open-circuit, and short-circuit bus conditions (see
Function Tables).
The SN75276 combines a 3-state, differential line driver and a differential input line receiver, both of which
operate from a single, 5-V power supply. The driver and receiver have active-high and active-low enables,
respectively, that can be externally connected together to function as a direction control. The driver differential
outputs and the receiver differential inputs are connected internally to form differential input/output (I/O) bus
ports that are designed to offer minimum loading to the bus whenever the driver is disabled or
V
CC
= 0. These ports feature wide positive and negative common-mode voltage ranges making the device
suitable for party-line applications.
The driver is designed for up to 60 mA of sink or source current. The driver features positive- and
negative-current limiting and thermal shutdown for protection from line fault conditions. Thermal shutdown is
designed to occur at a junction temperature of approximately 150°C. The receiver features a minimum input
impedance of 12 kΩ.
The SN75276 can be used in transmission line applications employing the SN75172 and SN75174 quadruple
differential line drivers and SN75173 and SN75175 quadruple differential line receivers.
SN75276 is characterized for operation from 0°C to 70°C.
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of
Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
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.
Copyright
©
1998, Texas Instruments Incorporated
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1
SN75276
FAIL-SAFE DIFFERENTIAL BUS TRANSCEIVER
SLLS212B – SEPTEMBER 1995 – REVISED APRIL 1998
Function Tables
EACH DRIVER
INPUT
D
H
L
X
ENABLE
DE
H
H
L
OUTPUTS
A
H
L
Z
B
L
H
Z
EACH RECEIVER
DIFFERENTIAL
A–B
VID
≥
0 V
– 0.3 V < VID < 0 V
VID
≤
– 0.3
X
Open
ENABLE
RE
L
L
L
H
L
OUTPUT
R
H
?
L
Z
H
H = high level, L = low level, ? = indeterminate,
X = irrelevant, Z = high impedance (off)
logic symbol
†
DE
RE
3
2
EN1
EN2
6
7
logic diagram (positive logic)
DE
D
RE
A
B
R
3
4
2
1
6
7
A
B
Bus
D
4
1
1
R
1
2
† This symbol is in accordance with ANSI/IEEE Std 91-1984
and IEC Publication 617-12.
2
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SN75276
FAIL-SAFE DIFFERENTIAL BUS TRANSCEIVER
SLLS212B – SEPTEMBER 1995 – REVISED APRIL 1998
schematics of inputs and outputs
EQUIVALENT OF EACH INPUT
VCC
R(eq)
TYPICAL OF A AND B I/O PORTS
VCC
180 kΩ
NOM
Connected
on A Port
Input
A or B
18 kΩ
NOM
3 kΩ
NOM
Output
TYPICAL OF RECEIVER OUTPUT
VCC
85
Ω
NOM
Driver input: R(eq) = 3 kΩ NOM
Enable inputs: R(eq) = 8 kΩ NOM
R(eq) = equivalent resistor
180 kΩ
NOM
Connected
on B Port
1.1 kΩ
NOM
absolute maximum ratings over operating free-air temperature range (unless otherwise noted)
†
Supply voltage, V
CC
(see Note 1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 V
Voltage at any bus terminal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . – 10 V to 15 V
Enable input voltage, V
I
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.5 V
Continuous total power dissipation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . See Dissipation Rating Table
Storage temperature range, T
stg
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . – 65°C to 150°C
Lead temperature 1,6 mm (1/16 inch) from case for 10 seconds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 260°C
† Stresses beyond those listed under “absolute maximum ratings” may cause permanent damage to the device. These are stress ratings only, and
functional operation of the device at these or any other conditions beyond those indicated under “recommended operating conditions” is not
implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.
NOTE 1: All voltage values, except differential input/output bus voltage, are with respect to network ground terminal.
DISSIPATION RATING TABLE
PACKAGE
D
P
TA
≤
25°C
POWER RATING
725 mW
1100 mW
DERATING FACTOR
ABOVE TA = 25°C
5.8 mW/°C
8.8 mW/°C
TA = 70°C
POWER RATING
464 mW
704 mW
TA = 105°C
POWER RATING
261 mW
396 mW
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SN75276
FAIL-SAFE DIFFERENTIAL BUS TRANSCEIVER
SLLS212B – SEPTEMBER 1995 – REVISED APRIL 1998
recommended operating conditions
MIN
Supply voltage, VCC
Voltage at any bus terminal (separately or common mode), VI or VIC
mode)
High-level input voltage, VIH
Low-level input voltage, VIL
Differential input voltage, VID (see Note 2)
High-level
High level output current IOH
current,
Low-level
Low level output current, IOL
current
Operating free-air temperature, TA
Driver
Receiver
Driver
Receiver
0
D, DE, and RE
D, DE, and RE
2
0.8
±
12
– 60
– 400
60
8
70
4.75
TYP
5
MAX
5.25
12
–7
UNIT
V
V
V
V
V
mA
µA
mA
°C
NOTE 2: Differential input/output bus voltage is measured at the noninverting terminal A with respect to the inverting terminal B.
4
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SN75276
FAIL-SAFE DIFFERENTIAL BUS TRANSCEIVER
SLLS212B – SEPTEMBER 1995 – REVISED APRIL 1998
DRIVER SECTION
electrical characteristics over recommended ranges of supply voltage and operating free-air
temperature (unless otherwise noted)
PARAMETER
VIK
VO
|VOD1|
|VOD2|
VOD3
∆|V
OD|
VOC
∆|V
OC|
IO
IIH
IIL
Input clamp voltage
Output voltage
Differential output voltage
Differential output voltage
Differential output voltage
Change in magnitude of differential output
g
g
¶
voltage
Common-mode
Common mode output voltage
Change in magnitude of common-mode
g
g
output voltage¶
Output current
High-level input current
Low-level input current
Output disabled,
,
See Note 4
VI = 2.4 V
VI = 0.4 V
VO = – 7 V
VO = 0
VO = VCC
VO = 12 V
No load
Outputs enabled
Outputs disabled
42
26
VO = 12 V
VO = – 7 V
RL = 54
Ω
or 100
Ω
Ω,
See Figure 1
TEST CONDITIONS†
II = – 18 mA
IO = 0
IO = 0
RL = 100
Ω,
RL = 54
Ω,
See Note 3
See Figure 1
See Figure 1
MIN
0
1.5
1/2 VOD1or 2§
1.5
1.5
2.5
5
5
±
0 2
0.2
+3
–1
±
0 2
0.2
1
– 0.8
20
– 400
– 250
150
250
250
70
35
mA
mA
3.6
TYP‡
MAX
– 1.5
6
6
UNIT
V
V
V
V
V
V
V
V
V
mA
µA
µA
IOS
Short-circuit
Short circuit output current
ICC
Supply current (total package)
† The power-off measurement in ANSI Standard TIA/EIA-422-B applies to disabled outputs only and is not applied to combined inputs and outputs.
‡ All typical values are at VCC = 5 V and TA = 25°C.
§ The minimum VOD2 with a 100-Ω load is either 1/2 VOD1 or 2 V, whichever is greater.
¶
∆|V
OD| and
∆|V
OC| 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.
NOTES: 3. This applies for both power on and off; refer to TIA/EIA-485-A for exact conditions. The TIA/EIA-422-B limit does not apply for a
combined driver and receiver terminal.
4. See TIA/EIA-485-A Figure 3.5, Test Termination Measurement 2.
switching characteristics, V
CC
= 5 V, R
L
= 110 kΩ, T
A
= 25°C (unless otherwise noted)
PARAMETER
td(OD)
tt(OD)
tPZH
tPZL
tPHZ
tPLZ
Differential-output delay time
Differential-output transition time
Output enable time to high level
Output enable time to low level
Output disable time from high level
Output disable time from low level
TEST CONDITIONS
RL = 54
Ω
Ω,
See Figure 4
See Figure 5
See Figure 4
See Figure 5
See Figure 3
MIN
TYP
15
20
85
40
150
20
MAX
22
30
120
60
250
30
UNIT
ns
ns
ns
ns
ns
ns
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