Datasheet

5 V, ±15 kV ESD Protected
Half-Duplex, RS-485/RS-422 Transceivers
ADM485E/ADM487E/ADM1487E
Rev. B
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FEATURES
TIA/EIA RS-485/RS-422 compliant
ESD protection on RS-485 I/O pins
±15 kV human body model (HBM)
Data rates
ADM487E: 250 kbps
ADM485E/ADM1487E: 2.5 Mbps
Half-duplex
Reduced slew rates for low EMI
Common-mode input range: −7 V to +12 V
Thermal shutdown and short-circuit protection
8-lead SOIC packages
ADM487EW qualified for automotive applications
APPLICATIONS
Energy/power metering
Lighting systems
Industrial control
Telecommunications
Security systems
Instrumentation
FUNCTIONAL BLOCK DIAGRAM
B
A
R
D
RO
RE
DE
DI
GND
V
CC
ADM485E/
ADM487E/
ADM1487E
06356-001
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
Industries 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
Half-/Full-
Duplex
Guaranteed
Data Rate
(Mbps)
Slew Rate
Limited
Low Power
Shutdown
Driver/Receiver
Enable
Quiescent
Current (μA)
Number of
Nodes on Bus
Pin
Count
ADM485E Half 2.5 No No Yes 300 32 8
ADM487E Half 0.25 Yes Yes Yes 120 128 8
ADM1487E Half 2.5 No No Yes 230 128 8