LTM2881



2881fa

Typical applicaTion

DescripTion

Complete Isolated

RS485/RS422 µModule

Transceiver + Power

components are required. A single supply powers both

sides of the interface through an integrated, isolated, low

noise, efficient 5V output DC/DC converter.

Coupled inductors and an isolation power transformer

and the logic interface. This device is ideal for systems

where the ground loop is broken allowing for large com-

mon mode voltage variation. Uninterrupted communica-

tion is guaranteed for common mode transients greater

than 30kV/μs.

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.

Enhanced ESD protection allows this part to withstand up

to ±15kV (human body model) on the transceiver interface

pins to isolated supplies and ±10kV through the isolation

barrier to logic supplies without latch-up or damage.

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.

Isolated Half-Duplex RS485 μModule Transceiver

FeaTures

applicaTions

n

n

Isolated DC Power: 5V at Up to 200mA

n

No External Components Required

n

20Mbps or Low EMI 250kbps Data Rate

n

High ESD: ±15kV HBM on Transceiver Interface

n

High Common Mode Transient Immunity: 30kV/μs

n

Integrated Selectable 120Ω Termination

n

3.3V (LTM2881-3) or 5.0V (LTM2881-5) Operation

n

1.62V to 5.5V Logic Supply Pin for Flexible Digital Interface

n

n

High Input Impedance Failsafe RS485 Receiver

n

Current Limited Drivers and Thermal Shutdown

n

Compatible with TIA/EIA-485-A Specification

n

High Impedance Output During Internal Fault Condition

n

Low Current Shutdown Mode (< 10µA)

n

General Purpose CMOS Isolated Channel

n

Small, Low Profile (15mm

× 11.25mm × 2.8mm)

Surface Mount BGA and LGA Packages

n

Isolated RS485/RS422 Interface

n

Industrial Networks

n

Breaking RS485 Ground Loops

2881 TA01

TWISTED-PAIR

CABLE

AVAILABLE CURRENT:

150mA (LTM2881-5)

100mA (LTM2881-3)

A

5V

RO

TE

RE

DE

DI

GND

GND2

3.3V

LTM2881

B

Y

Z

PWR

LTM2881 Operating Through 35kV/μs CM Transients

2881 TA01a

500V/DIV

50ns/DIV

1V/DIV

1V/DIV

DI

RO

MULTIPLE SWEEPS

OF COMMON MODE

TRANSIENTS