±15 kV ESD-Protected, 3.3 V,12 Mbps,
EIA RS-485/RS-422 Transceiver
ADM3485E
FEATURES
TIA/EIA RS-485/RS-422 compliant
±15 kV ESD protection on RS-485 input/output pins
12 Mbps data rate
Half-duplex transceiver
Up to 32 nodes on the bus
Receiver open-circuit, fail-safe design
Low power shutdown current
Outputs high-Z when disabled or powered off
Common-mode input range: −7 V to +12 V
Thermal shutdown and short-circuit protection
Industry-standard 75176 pinout
8-lead narrow SOIC package
FUNCTIONAL BLOCK DIAGRAM
ADM3485E
RO
R
RE
B
DE
A
DI
D
APPLICATIONS
Power/energy metering
Telecommunications
EMI-sensitive systems
Industrial control
Local area networks
03338-001
Figure 1.
GENERAL DESCRIPTION
The ADM3485E is a 3.3 V, low power data transceiver with
±15 kV ESD protection, suitable for half-duplex communi-
cation on multipoint bus transmission lines. The ADM3485E
is designed for balanced data transmission and complies with
TIA/EIA standards RS485 and RS-422. The ADM3485E is a
half-duplex transceiver that shares differential lines and has
separate enable inputs for the driver and the receiver.
The devices have a 12 kΩ receiver input impedance, which
allows up to 32 transceivers on a bus. Because only one driver
should be enabled at any time, the output of a disabled or
powered-down driver is tristated to avoid overloading the bus.
The receiver has a fail-safe feature that ensures a logic high
output when the inputs are floating. Excessive power dissipation
caused by bus contention or by output shorting is prevented
with a thermal shutdown circuit.
The part is fully specified over the industrial temperature range
and is available in an 8-lead narrow SOIC package.
Rev. D
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