Analog Devices ADM3491 Datasheet
3.3 V , Full Duplex, 840 mA
R
D
RE
DE
DI
A
B
Z
Y
ADM3491
RO
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.
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.
20 Mbps, EIA RS-485 Transceiver
ADM3491
FUNCTIONAL BLOCK DIAGRAM
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.
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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–SPECIFICA TIONS
(VCC = +3.3 V 6 0.3 V. All specifications T
MIN
to T
unless otherwise noted.)
MAX
Parameter Min Typ Max Units Test Conditions/Comments
DRIVER
Differential Output Voltage, V
∆|V
| for Complementary Output States 0.2 V R = 54 Ω or 100 Ω, Figure 1
OD
Common-Mode Output Voltage V
∆|V
| for Complementary Output States 0.2 V R = 54 Ω or 100 Ω, Figure 1
OC
CMOS Input Logic Threshold Low, V
OD
OC
INL
CMOS Input Logic Threshold High, V
2.0 V RL = 100 Ω, Figure 1, VCC > 3.1 V
1.5 V R
1.5 V R
= 54 Ω, Figure 1
L
= 60 Ω, Figure 2, –7 V < V
L
3 V R = 54 Ω or 100 Ω, Figure 1
0.8 V
2.0 V
INH
TST
Logic Input Current (DE, DI, RE) ±1.0 µA
Output Leakage (Y, Z) Current ±3 µAV
= –7 V or +12 V, VCC = 0 V or 3.6 V
O
Output Short Circuit Current ±250 mA VO = –7 V or +12 V
RECEIVER
Differential Input Threshold Voltage, V
Input Voltage Hysteresis, ∆V
TH
Input Resistance 12 19 kΩ –7 V < V
Input Current (A, B) +1 mA V
–0.2 +0.2 V –7 V < VCM < +12 V
TH
50 mV VCM = 0 V
= +12 V
–0.8 mA V
IN
= –7 V
IN
< +12 V
CM
Logic Enable Input Current (RE) ±1 µA
Output Voltage Low, V
Output Voltage High, V
OL
OH
VCC –0.4 V V I
Short Circuit Output Current ±60 mA V
Three-State Output Leakage Current ±1.0 µAV
0.4 V I
= +2.5 mA
OUT
= –1.5 mA
OUT
= GND or V
OUT
= 3.6 V, 0 V < V
CC
CC
OUT
< V
CC
POWER SUPPLY CURRENT
I
CC
0.84 1.2 mA DE = V
Outputs Unloaded,
, RE = 0 V
CC
0.84 1.2 mA DE = 0 V, RE = 0 V
Supply Current in Shutdown 0.002 1 µA DE = 0 V, RE = V
Specifications subject to change without notice.
CC
< +12 V
–2–
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ADM3491
TIMING SPECIFICATIONS
(VCC = +3.3 V, TA = +258C)
Parameter Min Typ Max Units Test Conditions/ Comments
DRIVER
Differential Output Delay T
DD
Differential Output Transition Time 1 8 15 ns R
Propagation Delay Input to Output T
Driver O/P to O/P T
SKEW
PLH
, T
PHL
135nsR
72235nsR
8nsR
= 60 Ω, CL1 = CL2 = 15 pF, Figure 5
L
= 60 Ω, CL1 = CL2 = 15 pF, Figure 5
L
= 27 Ω, CL1 = CL2 = 15 pF, Figure 6
L
= 54 Ω, CL1 = CL2 = 15 pF, Figure 6
L
ENABLE/DISABLE
Driver Enable to Output Valid 45 90 ns R
Driver Disable Timing 40 80 ns R
= 110 Ω, CL = 50 pF, Figure 3
L
= 110 Ω, CL = 50 pF, Figure 3
L
Driver Enable from Shutdown 650 110 ns RL = 110 Ω, CL = 15 pF, Figure 3
RECEIVER
Time to Shutdown 80 190 300 ns
Propagation Delay Input to Output T
Skew T
PLH–TPHL
Receiver Enable T
Receiver Disable T
EN
DEN
PLH
, T
PHL
25 65 90 ns CL = 15 pF, Figure 8
10 ns CL = 15 pF, Figure 8
25 50 ns CL = 15 pF, Figure 4
25 45 ns CL = 15 pF, Figure 4
Receiver Enable from Shutdown 500 ns CL = 15 pF, Figure 4
TIMING SPECIFICATIONS
(VCC = +3.3 V 6 0.3 V, TA = T
MIN
to T
MAX
)
Parameter Min Typ Max Units Test Conditions/ Comments
DRIVER
Differential Output Delay T
DD
Differential Output Transition Time 2 8 15 ns R
Propagation Delay Input to Output T
Driver O/P to O/P T
SKEW
PLH
, T
PHL
170nsR
72270nsR
= 60 Ω, CL1 = CL2 = 15 pF, Figure 5
L
= 60 Ω, CL1 = CL2 = 15 pF, Figure 5
L
= 27 Ω, CL1 = CL2 = 15 pF, Figure 6
L
10 ns RL = 54 Ω, CL1 = CL2 = 15 pF, Figure 6
ENABLE/DISABLE
Driver Enable to Output Valid 45 110 ns R
Driver Disable Timing 40 110 ns R
= 110 Ω, CL = 50 pF, Figure 3
L
= 110 Ω, CL = 50 pF, Figure 3
L
Driver Enable from Shutdown 650 110 ns RL = 110 Ω, CL = 15 pF, Figure 3
RECEIVER
Time to Shutdown 50 190 500 ns
Propagation Delay Input to Output T
Skew T
PLH–TPHL
Receiver Enable T
Receiver Disable T
EN
DEN
PLH
, T
PHL
25 65 115 ns CL = 15 pF, Figure 8
20 ns CL = 15 pF, Figure 8
25 50 ns CL = 15 pF, Figure 4
25 50 ns CL = 15 pF, Figure 4
Receiver Enable from Shutdown 600 ns CL = 15 pF, Figure 4
–3–REV. 0
ADM3491
ABSOLUTE MAXIMUM RATINGS*
(TA = +25°C unless otherwise noted)
VCC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +7 V
Inputs
Driver Input (DI) . . . . . . . . . . . . . . . .–0.3 V to V
Control Inputs (DE, RE) . . . . . . . . . .–0.3 V to V
+ 0.3 V
CC
+ 0.3 V
CC
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 V
+0.5 V
CC
Power Dissipation 14-Lead DIP . . . . . . . . . . . . . . . . 800 mW
θ
, Thermal Impedance . . . . . . . . . . . . . . . . . . . 140°C/W
JA
Power Dissipation 14-Lead SOIC . . . . . . . . . . . . . . . 650 mW
θ
, Thermal Impedance . . . . . . . . . . . . . . . . . . . 115°C/W
JA
ORDERING GUIDE
Power Dissipation 16-Lead TSSOP . . . . . . . . . . . . . . 500 mW
θ
, Thermal Impedance . . . . . . . . . . . . . . . . . . . 158 °C/W
JA
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
*Stresses above those listed under Absolute Maximum Ratings may cause perma-
nent 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.
Model Temperature Range Package Description Package Options
ADM3491AN –40°C to +85°C Plastic DIP N-14
ADM3491AR –40°C to +85°C Small Outline (SOIC) R-14
ADM3491ARU –40°C to +85°C Thin Shrink Small Outline (TSSOP) RU-16
–4–
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