LTM2881
Complete Isolated
RS485/RS422 µModule
Transceiver + Power
FEATURES
DESCRIPTION
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Isolator ꢀModule Technology
The LTM®2881 is a complete galvanically isolated full-
duplex RS485/RS422 μModule® transceiver. No external
components are required. A single supply powers both
sides of the interface through an integrated, isolated, low
noise, efficient 5V output DC/DC converter.
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Isolated RS485/RS422 Transceiver: 2500V
RMS
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Integrated Isolated DC/DC Converter: 1W, 62% Efficiency
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No External Components Required
20Mbps or Low EMI 250kbps Data Rate
High ESD: 15kV HꢁM on Transceiver Interface
High Common Mode Transient Immunity: 30kV/μs
Integrated Selectable 120Ω Termination
Coupledinductorsandanisolationpowertransformerprovide
2500V
of isolation between the line transceiver and the
RMS
logic interface. This device is ideal for systems where the
ground loop is broken allowing for large common mode
voltagevariation.Uninterruptedcommunicationisguaranteed
for common mode transients greater than 30kV/ꢀs.
3.3V ꢁLTM2881-3ꢂ or 5.0V ꢁLTM2881-5ꢂ Operation
1.62V to 5.5V Logic Supply Pin for Flexible Digital Interface
Common Mode Working Voltage: 560V
PEAK
High Input Impedance Failsafe RS485 Receiver
Current Limited Drivers and Thermal Shutdown
Compatible with TIA/EIA-485-A Specification
High Impedance Output During Internal Fault Condition
Low Current Shutdown Mode ꢁ< 10μAꢂ
Maximum data rates are 20Mbps or 250kbps in slew
limited mode. Transmit data, DI and receive data, RO, are
implemented with event driven low jitter processing. The
receiver has a one-eighth unit load supporting up to 256
nodes per bus. A logic supply pin allows easy interfacing
with different logic levels from 1.62V to 5.5V, independent
of the main supply.
General Purpose CMOS Isolated Channel
Small, Low Profile ꢁ15mm × 11.25mm × 2.8mmꢂ
Surface Mount LGA Package
Enhanced ESD protection allows this part to withstand up
to 15kVꢁhumanbodymodelꢂonthetransceiverinterface
pins to isolated supplies and 10kV through the isolation
barrier to logic supplies without latch-up or damage.
APPLICATIONS
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Isolated RS485/RS422 Interface
Industrial Networks
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Breaking RS485 Ground Loops
L, LT, LTC, LTM, Linear Technology, μModule and the Linear logo are registered trademarks of
Linear Technology Corporation. All other trademarks are the property of their respective owners.
TYPICAL APPLICATION
Isolated Half-Duplex RS485 μModule Transceiver
LTM2881 Operating Through 35kV/μs CM Transient
3.3V
MULTIPLE SWEEPS
OF COMMON MODE
TRANSIENTS
V
CC
LTM2881
PWR
500V/DIV
V
L
A
B
RO
DI
RE
RO
TWISTED-PAIR
CABLE
1V/DIV
1V/DIV
TE
DE
Y
Z
DI
2881 TA01a
50ns/DIV
GND
GND2
2881 TA01
2881f
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