a
ESD Protected, EMC Compliant, 3.3 V,
20 Mbps, EIA RS-485 Transceiver
ADM3485E
FUNCTIONAL BLOCK DIAGRAM
ADM3485E
FEATURES
Operates with +3.3 V Supply
ESD Protection: 8 kV Meets IEC1000-4-2
EFT Protection: 2 kV Meets IEC1000-4-4
EIA RS-422 and RS-485 Compliant Over Full CM Range
19 k 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
1 mA Supply Current
2 nA Shutdown Current
8 ns Skew
APPLICATIONS
Telecommunications
DTE-DCE Interface
Packet Switching
Local Area Networks
Data Concentration
Data Multiplexers
Integrated Services Digital Network (ISDN)
AppleTalk
Industrial Controls
RO
R
RE
B
DE
A
DI
D
GENERAL DESCRIPTION
The ADM3485E is a low power differential line transceiver
designed to operate using a single +3.3 V power supply. Low
power consumption makes it ideal for power sensitive applica-
tions. It is suitable for communication on multipoint bus trans-
mission lines. Internal protection against electrostatic discharge
(ESD) and electrical fast transient (EFT) allows operation in
electrically harsh environments.
It is intended for balanced data transmission and complies with
both EIA Standards RS-485 and RS-422. It contains a differen-
tial line driver and a differential line receiver, and is suitable for
half 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.
The receiver contains a fail-safe feature that results in a
logic high output state if the inputs are unconnected
(floating).
The ADM3485E is fabricated on BiCMOS, an advanced
mixed technology process combining low power CMOS
with fast switching bipolar technology.
The ADM3485E is fully specified over the industrial tem-
perature range and is available in 8-lead DIP and SOIC
packages.
REV. A
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., 2000
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