3.3 V, Full-Duplex, 840 μA,
20 Mbps, EIA RS-485 Transceiver
Data Sheet
ADM3491-1
FEATURES
FUNCTIONAL BLOCK DIAGRAM
Operates with 3.3 V supply
EIA RS-422 and RS-485 compliant over full CM range
19 kΩ input impedance
ADM3491-1
A
Up to 50 transceivers on bus
20 Mbps data rate
RO
R
B
RE
DE
Short-circuit protection
Specified over full temperature range
Thermal shutdown
Z
Y
Interoperable with 5 V logic
840 μA supply current
2 nA shutdown current
D
DI
Available in PDIP, SOIC, and TSSOP
Meets IEC1000-4-4 (>1 kV)
8 ns skew
Figure 1.
Upgrade for MAX3491, 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 ADM3491-1 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, makes it
ideal for power-sensitive applications. It is suitable for commu-
nication on multipoint bus transmission lines.
The input impedance is 19 kΩ, allowing up to 50 transceivers to
be connected on the bus. A thermal shutdown circuit prevents
excessive power dissipation caused by bus contention or by
output shorting. This feature forces the driver output into a high
impedance state if a significant temperature increase is detected
in the internal driver circuitry during fault conditions.
The ADM3491-1 is intended for balanced data transmission
and complies with both Electronic Industries Association (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.
If the inputs are unconnected (floating), the receiver contains a
fail-safe feature that results in a logic high output state.
The ADM3491-1 is fabricated on BiCMOS, an advanced mixed
technology process combining low power CMOS with fast
switching bipolar technology.
Rev. C
Document Feedback
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 that may result from its use. Specifications subject to change without notice. No
license is granted by implication or otherwise under any patent or patent rights of Analog Devices.
Trademarks and registeredtrademarks arethe property of their respective owners.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781.329.4700 ©1998–2014 Analog Devices, Inc. All rights reserved.
Technical Support
www.analog.com