5 V, ±15 kV ESD Protected
Half-Duplex, RS-485/RS-422 Transceivers
ADM485E/ADM487E/ADM1487E
FEATURES
TIA/EIA RS-485-/RS-422-compliant
ESD protection on RS-485 I/O pins
±15 kV human body model
Data rates
ADM487E: 250 kbps
ADM485E/ADM1487E: 2.5 Mbps
Half-duplex options
Reduced slew rates for low EMI
−7 V to +12 V common-mode input range
Thermal shutdown and short-circuit protection
8-lead SOIC packages
FUNCTIONAL BLOCK DIAGRAM
V
CC
ADM485E/
ADM487E/
ADM1487E
RO
RE
DE
DI
D
06356-001
R
A
B
APPLICATIONS
Energy/power metering
Lighting systems
Industrial control
Telecommunications
Security systems
Instrumentation
GND
Figure 1.
GENERAL DESCRIPTION
The ADM485E/ADM487E/ADM1487E are 5 V, low power
data transceivers with ±15 kV ESD protection suitable for half-
duplex communication on multipoint bus transmission lines.
They are designed for balanced data transmission and comply
with Telecommunication Industry Association/Electronics Indus-
tries Association (TIA/EIA) standards RS-485 and RS-422. The
ADM487E and ADM1487E have a 1/4 unit load receiver input
impedance that allows up to 128 transceivers on a bus, whereas
the ADM485E allows up to 32 transceivers on a bus. Because
only one driver is enabled at any time, the output of a disabled or
power-down driver is three-stated to avoid overloading the bus.
The driver outputs are slew rate-limited to reduce EMI and data
errors caused by reflections from improperly terminated buses.
Excessive power dissipation caused by bus contention or output
shorting is prevented with a thermal shutdown circuit.
The parts are fully specified over the industrial temperature
ranges and are available in 8-lead SOIC packages.
Table 1. Selection Table
Part
Number
ADM485E
ADM487E
ADM1487E
Half-/Full-
Duplex
Half
Half
Half
Guaranteed
Data Rate
(Mbps)
2.5
0.25
2.5
Slew Rate
Limited
No
Yes
No
Low Power
Shutdown
No
Yes
No
Driver/Receiver
Enable
Yes
Yes
Yes
Quiescent
Current (μA)
300
120
230
Number of
Nodes on Bus
32
128
128
Pin
Count
8
8
8
Rev. 0
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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
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©2007 Analog Devices, Inc. All rights reserved.
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