LTC2879X

1

Rev 0

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TYPICAL APPLICATION

FEATURES

DESCRIPTION

±60V Fault Tolerant

RS485/RS422 Transceiver

with Operation to 175°C

The LTC®2879X is a rugged RS485/RS422 transceiver

designed to operate over a wide temperature range of

–55°C to 175°C. Special processing steps are used to

prevent intermetallic growth that can cause metal voids

on standard parts operating at high temperatures. Low-

drift, low-leakage circuitry and lack of a thermal shutdown

circuit allow the LTC2879X to meet critical specifications,

tested 100% at 175°C.

The LTC2879X also meets the specifications for

PROFIBUS-DP (IEC 61158-2) supporting all data rates

from 9.6kbps to 12Mbps.

The LTC2879X is exceptionally robust, tolerating ±60V

faults on the bus pins and protected to ±52kV ESD. These

devices are suitable for harsh environments or where 24V

power might be inadvertently connected. Extended ±25V

input common mode operating range and full failsafe

operation improve data communication reliability in noisy

systems.

The LTC2879X meets RS485, RS422, and PROFIBUS-DP

specifications with a supply voltage of 4.5V to 5.5V with

full RS485/RS422 compatibility down to 3V.

APPLICATIONS

n

Guaranteed Operation from –55°C to 175°C

n

Fully Tested at 175°C

n

Protected from Overvoltage Line Faults to ±60V

n

±52kV ESD Interface Pins, ±15kV All Other Pins

n

Level 4 IEC61000-4-4 Electrical Fast Transient

n

±25V Working Common Mode Range

n

20Mbps Maximum Baud Rate

n

Operates with VCC from 3V to 5.5V

n

PROFIBUS IEC 61158-2 Compliant (VCC ≥ 4.5V)

n

Fully Balanced Differential Receiver Thresholds with

240mV Hysteresis for Superior Noise Tolerance and

Low Duty Cycle Distortion

n

Receiver Failsafe for Open, Shorted and Terminated

Conditions

n

Available in a Tiny 3mm × 3mm MSOP Package

n

Oil and Gas Exploration

n

High Temperature Industrial Control

n

PROFIBUS-DP

n

Military Systems

n

Harsh Environments

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VCC

GND

DI

RE

RO

DE

B

A

0.1µF

LTC2879X

SENSOR

120

3V TO 5.5V

RS485

CABLE

ZO = 120Ω

µC

120

2879X TA01a

175°C, 20Mbps, VCC = 5V

50ns/DIV

DI

5V/DIV

A AND B

2V/DIV

RO

5V/DIV

A–B

2V/DIV

2879X TA01b

RL = 54

CL = 100pF (FIGURE 5)