AD ADM3491AN 3.3 v, full duplex, 840 ua 20 mbps, eia rs-485 transceiver Datasheet

a
FEATURES
Operates with +3.3 V Supply
EIA RS-422 and RS-485 Compliant Over Full CM Range
19 kV Input Impedance
Up to 50 Transceivers on Bus
20 Mbps Data Rate
Short Circuit Protection
Specified Over Full Temperature Range
Thermal Shutdown
Interoperable with 5 V Logic
840 mA Supply Current
2 nA Shutdown Current
Also Available in TSSOP Package
Meets IEC1000-4-4 (>1 kV)
8 ns Skew
Upgrade for MAX 3491, SN75ALS180
APPLICATIONS
Telecommunications
DTE-DCE Interface
Packet Switching
Local Area Networks
Data Concentration
Data Multiplexers
Integrated Services Digital Network (ISDN)
AppleTalk
Industrial Controls
GENERAL DESCRIPTION
The ADM3491 is a low power differential line transceiver
designed to operate using a single +3.3 V power supply. Low
power consumption coupled with a shutdown mode make it
ideal for power sensitive applications. It is suitable for communication on multipoint bus transmission lines.
3.3 V, Full Duplex, 840 mA
20 Mbps, EIA RS-485 Transceiver
ADM3491
FUNCTIONAL BLOCK DIAGRAM
ADM3491
A
RO
R
B
RE
DE
Z
DI
D
Y
The receiver contains a fail-safe feature that results in a
logic high output state if the inputs are unconnected
(floating).
The ADM3491 is fabricated on BiCMOS, an advanced
mixed technology process combining low power CMOS
with fast switching bipolar technology.
The ADM3491 is fully specified over the industrial temperature range and is available in DIP and SOIC packages
as well as a new space saving TSSOP package.
It is intended for balanced data transmission and complies with
both EIA Standards RS-485 and RS-422. It contains a differential line driver and a differential line receiver, making it suitable
for full duplex data transfer.
The input impedance is 19 kΩ allowing up to 50 transceivers to
be connected on the bus.
Excessive power dissipation caused by bus contention or by
output shorting is prevented by a thermal shutdown circuit.
This feature forces the driver output into a high impedance state
if, during fault conditions, a significant temperature increase is
detected in the internal driver circuitry.
REV. 0
Information furnished by Analog Devices is believed to be accurate and
reliable. However, no responsibility is assumed by Analog Devices for its
use, nor for any infringements of patents or other rights of third parties
which may result from its use. No license is granted by implication or
otherwise under any patent or patent rights of Analog Devices.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781/329-4700
World Wide Web Site: http://www.analog.com
Fax: 781/326-8703
© Analog Devices, Inc., 1998
ADM3491–SPECIFICATIONS (V
Parameter
DRIVER
Differential Output Voltage, VOD
∆|VOD| for Complementary Output States
Common-Mode Output Voltage VOC
∆|VOC| for Complementary Output States
CMOS Input Logic Threshold Low, VINL
CMOS Input Logic Threshold High, VINH
Logic Input Current (DE, DI, RE)
Output Leakage (Y, Z) Current
Output Short Circuit Current
RECEIVER
Differential Input Threshold Voltage, VTH
Input Voltage Hysteresis, ∆VTH
Input Resistance
Input Current (A, B)
Logic Enable Input Current (RE)
Output Voltage Low, VOL
Output Voltage High, VOH
Short Circuit Output Current
Three-State Output Leakage Current
CC
Min
= +3.3 V 6 0.3 V. All specifications TMIN to TMAX unless otherwise noted.)
Typ
Max
Units
Test Conditions/Comments
V
V
V
V
V
V
V
V
µA
µA
mA
RL = 100 Ω, Figure 1, VCC > 3.1 V
RL = 54 Ω, Figure 1
RL = 60 Ω, Figure 2, –7 V < VTST < +12 V
R = 54 Ω or 100 Ω, Figure 1
R = 54 Ω or 100 Ω, Figure 1
R = 54 Ω or 100 Ω, Figure 1
–7 V < VCM < +12 V
VCM = 0 V
–7 V < VCM < +12 V
VIN = +12 V
VIN = –7 V
± 60
± 1.0
V
mV
kΩ
mA
mA
µA
V
V
mA
µA
1.2
1.2
1
mA
mA
µA
2.0
1.5
1.5
0.2
3
0.2
0.8
2.0
± 1.0
±3
± 250
–0.2
12
+0.2
50
19
+1
–0.8
±1
0.4
VCC –0.4 V
POWER SUPPLY CURRENT
ICC
Supply Current in Shutdown
0.84
0.84
0.002
VO = –7 V or +12 V, VCC = 0 V or 3.6 V
VO = –7 V or +12 V
IOUT = +2.5 mA
IOUT = –1.5 mA
VOUT = GND or VCC
VCC = 3.6 V, 0 V < VOUT < VCC
Outputs Unloaded,
DE = VCC, RE = 0 V
DE = 0 V, RE = 0 V
DE = 0 V, RE = VCC
Specifications subject to change without notice.
–2–
REV. 0
ADM3491
TIMING SPECIFICATIONS (V
CC
= +3.3 V, TA = +258C)
Parameter
Min
Typ
Max
Units
Test Conditions/ Comments
DRIVER
Differential Output Delay TDD
Differential Output Transition Time
Propagation Delay Input to Output TPLH, TPHL
Driver O/P to O/P TSKEW
1
1
7
8
22
35
15
35
8
ns
ns
ns
ns
RL = 60 Ω, CL1 = CL2 = 15 pF, Figure 5
RL = 60 Ω, CL1 = CL2 = 15 pF, Figure 5
RL = 27 Ω, CL1 = CL2 = 15 pF, Figure 6
RL = 54 Ω, CL1 = CL2 = 15 pF, Figure 6
45
40
650
90
80
110
ns
ns
ns
RL = 110 Ω, CL = 50 pF, Figure 3
RL = 110 Ω, CL = 50 pF, Figure 3
RL = 110 Ω, CL = 15 pF, Figure 3
190
65
300
90
10
50
45
500
ns
ns
ns
ns
ns
ns
CL = 15 pF, Figure 8
CL = 15 pF, Figure 8
CL = 15 pF, Figure 4
CL = 15 pF, Figure 4
CL = 15 pF, Figure 4
ENABLE/DISABLE
Driver Enable to Output Valid
Driver Disable Timing
Driver Enable from Shutdown
RECEIVER
Time to Shutdown
Propagation Delay Input to Output TPLH, TPHL
Skew TPLH–TPHL
Receiver Enable TEN
Receiver Disable TDEN
Receiver Enable from Shutdown
TIMING SPECIFICATIONS (V
CC
80
25
25
25
= +3.3 V 6 0.3 V, TA = TMIN to TMAX)
Parameter
Min
Typ
Max
Units
Test Conditions/ Comments
DRIVER
Differential Output Delay TDD
Differential Output Transition Time
Propagation Delay Input to Output TPLH, TPHL
Driver O/P to O/P TSKEW
1
2
7
8
22
70
15
70
10
ns
ns
ns
ns
RL = 60 Ω, CL1 = CL2 = 15 pF, Figure 5
RL = 60 Ω, CL1 = CL2 = 15 pF, Figure 5
RL = 27 Ω, CL1 = CL2 = 15 pF, Figure 6
RL = 54 Ω, CL1 = CL2 = 15 pF, Figure 6
45
40
650
110
110
110
ns
ns
ns
RL = 110 Ω, CL = 50 pF, Figure 3
RL = 110 Ω, CL = 50 pF, Figure 3
RL = 110 Ω, CL = 15 pF, Figure 3
190
65
500
115
20
50
50
600
ns
ns
ns
ns
ns
ns
CL = 15 pF, Figure 8
CL = 15 pF, Figure 8
CL = 15 pF, Figure 4
CL = 15 pF, Figure 4
CL = 15 pF, Figure 4
ENABLE/DISABLE
Driver Enable to Output Valid
Driver Disable Timing
Driver Enable from Shutdown
RECEIVER
Time to Shutdown
Propagation Delay Input to Output TPLH, TPHL
Skew TPLH–TPHL
Receiver Enable TEN
Receiver Disable TDEN
Receiver Enable from Shutdown
REV. 0
50
25
25
25
–3–
ADM3491
Power Dissipation 16-Lead TSSOP . . . . . . . . . . . . . . 500 mW
θJA, Thermal Impedance . . . . . . . . . . . . . . . . . . . 158 °C/W
Operating Temperature Range
Industrial (A Version) . . . . . . . . . . . . . . . . –40°C to +85°C
Storage Temperature Range . . . . . . . . . . . . –65°C to +150°C
Lead Temperature (Soldering, 10 sec) . . . . . . . . . . . . +300°C
Vapor Phase (60 sec) . . . . . . . . . . . . . . . . . . . . . . . . +215°C
Infrared (15 sec) . . . . . . . . . . . . . . . . . . . . . . . . . . .+220°C
ESD Rating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . >2 kV
EFT Rating (IEC1000-4-4) . . . . . . . . . . . . . . . . . . . . . . >1 kV
ABSOLUTE MAXIMUM RATINGS*
(TA = +25°C unless otherwise noted)
VCC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +7 V
Inputs
Driver Input (DI) . . . . . . . . . . . . . . . .–0.3 V to VCC + 0.3 V
Control Inputs (DE, RE) . . . . . . . . . .–0.3 V to VCC + 0.3 V
Receiver Inputs (A, B) . . . . . . . . . . . . . . . –7.5 V to +12.5 V
Outputs
Driver Outputs . . . . . . . . . . . . . . . . . . . . . –7.5 V to +12.5 V
Receiver Output . . . . . . . . . . . . . . . . . –0.5 V to VCC +0.5 V
Power Dissipation 14-Lead DIP . . . . . . . . . . . . . . . . 800 mW
θJA, Thermal Impedance . . . . . . . . . . . . . . . . . . . 140°C/W
Power Dissipation 14-Lead SOIC . . . . . . . . . . . . . . . 650 mW
θJA, Thermal Impedance . . . . . . . . . . . . . . . . . . . 115°C/W
*Stresses above those listed under Absolute Maximum Ratings may cause permanent damage to the device. This is a stress rating only; functional operation of the
device at these or any other conditions above those listed in the operational
sections of this specification is not implied. Exposure to absolute maximum
ratings for extended periods of time may affect device reliability.
ORDERING GUIDE
Model
Temperature Range
Package Description
Package Options
ADM3491AN
ADM3491AR
ADM3491ARU
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
Plastic DIP
Small Outline (SOIC)
Thin Shrink Small Outline (TSSOP)
N-14
R-14
RU-16
–4–
REV. 0
ADM3491
PIN CONFIGURATION
DIP/SOIC
NC 1
14
VCC
RO 2
13
VCC
ADM3491
RE 3
12 A
TOP VIEW
DE 4 (Not to Scale) 11 B
DI 5
10
Z
GND 6
9
Y
GND 7
8
NC
NC = NO CONNECT
TSSOP
VCC 1
16
NC
NC 2
15
A
RO 3
14
B
ADM3491
RE 4
13
NC
TOP VIEW
DE 5 (Not to Scale) 12 Z
DI 6
11
Y
NC 7
10
NC
GND 8
9
NC
NC = NO CONNECT
PIN FUNCTION DESCRIPTIONS
Mnemonic
Pin
DIP/
SOIC
NC
1, 8
RO
RE
2
3
2, 7, 9, 10,
13, 16
3
4
DE
4
5
DI
5
6
GND
Y
Z
B
A
VCC
6, 7
9
10
11
12
13, 14
8
11
12
14
15
1
REV. 0
TSSOP
Function
No Connect.
Receiver Output. High when A > B by 200 mV or Low when A < B by 200 mV.
Receiver Output Enable. With RE low, the receiver output RO is enabled. With RE high,
the output goes high impedance. If RE is high and DE low, the ADM3491 enters a
shutdown state.
Driver Output Enable. A high level enables the driver differential outputs, Y and Z. A low
level places it in a high impedance state.
Driver Input. When the driver is enabled, a logic Low on DI forces Y low and Z high while
a logic high on DI forces Y high and Z low.
Ground Connection, 0 V.
Noninverting Driver Output Y.
Inverting Driver Output Z.
Inverting Receiver Input B.
Noninverting Receiver Input A.
Power Supply, 3.3 V ± 0.3 V.
–5–
ADM3491
Test Circuits
375V
R/2
VOD
VOD3
R/2
VTST
RL
VOC
VCC
375V
Figure 1. Driver Voltage Measurement Test Circuit
Figure 5. Driver Voltage Measurement Test Circuit 2
VCC
0V OR 3V
DE
RL
S1
RL
S1
S2
CL
VOUT
DE IN
VCC
+1.5V
RE
–1.5V
RE IN
Figure 2. Driver Enable/Disable Test Circuit
S2
CL
VOUT
Figure 6. Receiver Enable/Disable Test Circuit
VOM
DI
RL
CL1
RLDIFF
D
VOUT
CL2
DE
IN
VOUT
S1
CL
VCC
Figure 3. Driver Differential Output Delay Test Circuit
Figure 7. Driver Propagation Delay Test Circuit
3V
DI
CL1
D
RLDIFF
A
B
CL2
0V
RO
R
VID
RE
+1.5V
Figure 4. Driver/Receiver Propagation Delay Test Circuit
RE
CL VOUT
Figure 8. Receiver Propagation Delay Test Circuit
–6–
REV. 0
ADM3491
Switching Characteristics
3V
3V
1.5V
1.5V
tPLH
0V
Z
RE
1.5V
1.5V
0V
tPHL
tZL
tLZ
1/2VO
VO
1.5V
R
Y
tSKEW
tSKEW
VO
90% POINT
VOL + 0.25V
VOL
tHZ
tZH
90% POINT
0V
–VO
O/P
LOW
VOH
O/P HIGH
10% POINT
10% POINT
tR
R
tF
VOH – 0.25V
1.5V
0V
Figure 9. Driver Propagation Delay, Rise/Fall Timing
Figure 11. Driver Enable/Disable Timing
3V
RE
1.5V
1.5V
0V
A–B
0V
0V
t PLH
t PHL
tZL
tLZ
1.5V
R
VOH
O/P
LOW
VOL
tHZ
tZH
1.5V
VOL + 0.25V
1.5V
RO
O/P HIGH
R
VOL
1.5V
VOH
VOH – 0.25V
0V
Figure 10. Receiver Propagation Delay
REV. 0
Figure 12. Receiver Enable/Disable Timing
–7–
14
14
12
12
OUTPUT CURRENT – mA
OUTPUT CURRENT – mA
ADM3491–Typical Performance Characteristics
10
8
6
4
8
6
4
2
2
0
10
0
0
0.5
1
1.5
2
2.5
3
3.5
0
0 .5
Figure 13. Receiver Output Low Voltage vs. Output
Current
1.5
2
2.5
3
3.5
4
Figure 16. Receiver Output High Voltage vs. Output
Current
3.3
0.8
0.7
3.25
0.6
OUTPUT VOLTAGE – V
OUTPUT VOLTAGE – V
1
OUTPUT HIGH VOLTAGE – Volts
OUTPUT VOLTAGE – Volts
0.5
IRO = 2.5mA
0.4
0.3
3.2
IRO = –1.5mA
3.15
3.1
0.2
3.05
0.1
0
–40
–20
0
20
40
60
80
3
–40
100
–20
0
20
40
60
80
100
TEMPERATURE – 8C
TEMPERATURE – 8C
Figure 14. Receiver Output Low Voltage vs. Temperature
Figure 17. Receiver Output High Voltage vs. Temperature
120
2.6
2.5
100
OUTPUT VOLTAGE – V
OUTPUT CURRENT – mA
2.4
80
60
40
2.3
2.2
2.1
2.0
1.9
1.8
20
1.7
0
0
0.5
1
1.5
2
2.5
DIFFERENTIAL O/P VOLTAGE – Volts
1.6
–40
3
–20
0
20
40
60
80
100
TEMPERATURE – 8C
Figure 15. Driver Differential Output Voltage vs. Output
Current
Figure 18. Driver Differential Output Voltage vs.
Temperature
–8–
REV. 0
ADM3491
[
1.2
]
100FT CAT 5
CABLE
T
1.1
SUPPLY CURRENT – mA
T
3
T
1
T
0.9
1
2
0.8
T
4
0.7
–40
–20
0
20
40
60
80
100
CH1 1.00V
CH3 2.00V
TEMPERATURE – 8C
Figure 19. Supply Current vs. Temperature
[
T
CH2 1.00V
CH4 2.00V
M40.0ns CH3
640mV
Figure 21. Driving 100 ft. Cable H-L Transition
]
100
3
SHUTDOWN CURRENT – mA
90
100FT
CABLE
T
T
1
2
T
T
80
70
60
50
40
30
20
4
10
CH1 1.00V
CH3 2.00V
CH2 1.00V
CH4 2.00V
M40.0ns CH3
0
–40
640mV
Figure 20. Driving 100 ft. Cable L-H Transition
REV. 0
–20
0
20
40
TEMPERATURE – 8C
60
80
Figure 22. Shutdown Current vs. Temperature
–9–
ADM3491
+3.3V
+3.3V
0.1mF
RE
0.1mF
VCC
VCC
A
Y
B
Z
DE
DI
RO
R
RS-485/RS-422 LINK
ADM3491
D
ADM3491
Z
B
Y
A
RO
DI
D
R
RE
DE
GND
GND
Figure 23. ADM3491 Full-Duplex Data Link
Table I. Transmitting Truth Table
Transmitting
Inputs
Outputs
RE
DE
DI
Z
Y
X
X
0
1
1
1
0
0
1
0
X
X
0
1
Hi-Z
Hi-Z
1
0
Hi-Z
Hi-Z
Table II. Receiving Truth Table
Receiving
Inputs
Outputs
RE
DE
A–B
RO
0
0
0
1
X
X
X
X
> +0.2 V
< –0.2 V
Inputs O/C
X
1
0
1
Hi-Z
–10–
REV. 0
ADM3491
APPLICATIONS INFORMATION
Differential Data Transmission
Cable and Data Rate
Differential data transmission is used to reliably transmit data at
high rates over long distances and through noisy environments.
Differential transmission nullifies the effects of ground shifts
and noise signals which appear as common-mode voltages on
the line.
Two main standards are approved by the Electronics Industries
Association (EIA) which specify the electrical characteristics of
transceivers used in differential data transmission. The RS-422
standard specifies data rates up to 10 MBaud and line lengths
up to 4000 ft. A single driver can drive a transmission line with
up to 10 receivers.
The RS-485 standard was defined to cater to true multipoint
communications. This standard meets or exceeds all the requirements of RS-422, but also allows multiple drivers and
receivers to be connected to a single bus. An extended common
mode range of –7 V to +12 V is defined.
The most significant difference between RS-422 and RS-485 is
the fact that the drivers may be disabled thereby allowing more
than one to be connected to a single line. Only one driver should
be enabled at a time, but the RS-485 standard contains additional specifications to guarantee device safety in the event of
line contention.
The transmission line of choice for RS-485 communications is a
twisted pair. Twisted pair cable tends to cancel common-mode
noise and also causes cancellation of the magnetic fields generated by the current flowing through each wire, thereby reducing
the effective inductance of the pair.
The ADM3491 is designed for bidirectional data communications on multipoint transmission lines. A typical application
showing a multipoint transmission network is illustrated in
Figure 23. Only one driver can transmit at a particular time, but
multiple receivers may be enabled simultaneously.
As with any transmission line, it is important that reflections are
minimized. This may be achieved by terminating the extreme
ends of the line using resistors equal to the characteristic impedance of the line. Stub lengths of the main line should also be
kept as short as possible. A properly terminated transmission
line appears purely resistive to the driver.
Receiver Open-Circuit Fail Safe
The receiver input includes a fail-safe feature that guarantees a
logic high on the receiver when the inputs are open circuit or
floating.
Table III. Comparison of RS-422 and RS-485 Interface Standards
REV. 0
Specification
RS-422
RS-485
Transmission Type
Maximum Cable Length
Minimum Driver Output Voltage
Driver Load Impedance
Receiver Input Resistance
Receiver Input Sensitivity
Receiver Input Voltage Range
Differential
4000 ft.
±2 V
100 Ω
4 kΩ min
± 200 mV
–7 V to +7 V
Differential
4000 ft.
± 1.5 V
54 Ω
12 kΩ min
± 200 mV
–7 V to +12 V
–11–
ADM3491
OUTLINE DIMENSIONS
Dimensions shown in inches and (mm).
14-Lead Plastic DIP
(N-14)
0.795 (20.19)
0.725 (18.42)
0.3444 (8.75)
0.3367 (8.55)
7
0.160 (4.06)
0.115 (2.93)
0.022 (0.558)
0.014 (0.356)
0.060 (1.52)
0.015 (0.38)
14
8
1
7
PIN 1
0.0098 (0.25)
0.0040 (0.10)
0.130
(3.30)
MIN
0.100 0.070 (1.77)
(2.54) 0.045 (1.15)
BSC
0.1574 (4.00)
0.1497 (3.80)
0.325 (8.25)
0.300 (7.62) 0.195 (4.95)
0.115 (2.93)
0.015 (0.381)
0.008 (0.204)
SEATING
PLANE
SEATING
PLANE
0.0500
(1.27)
BSC
0.2440 (6.20)
0.2284 (5.80)
0.0688 (1.75)
0.0532 (1.35)
0.0192 (0.49)
0.0138 (0.35)
0.0099 (0.25)
0.0075 (0.19)
0.0196 (0.50)
x 45°
0.0099 (0.25)
8°
0°
0.0500 (1.27)
0.0160 (0.41)
16-Lead Thin Shrink Small Outline (TSSOP)
(RU-16)
0.201 (5.10)
0.193 (4.90)
16
9
0.177 (4.50)
0.169 (4.30)
PIN 1
0.280 (7.11)
0.240 (6.10)
1
8
PIN 1
0.006 (0.15)
0.002 (0.05)
SEATING
PLANE
0.0433
(1.10)
MAX
0.0256
(0.65)
BSC
0.0118 (0.30)
0.0075 (0.19)
0.0079 (0.20)
0.0035 (0.090)
8°
0°
0.028 (0.70)
0.020 (0.50)
PRINTED IN U.S.A.
8
1
0.256 (6.50)
0.246 (6.25)
14
0.210 (5.33)
MAX
C3216–8–1/98
14-Lead Narrow Body Small Outline (SOIC)
(R-14)
–12–
REV. 0