General Description

The MAX3158 is a high CMRR RS-485/RS-422 data-com-

munications interface providing ±60V isolation in a

hybrid microcircuit. A single +5V supply on the logic side

powers both sides of the interface, with external 100V

capacitors transferring power from the logic side to the

isolated side. Each MAX3158 contains one transmitter

and one receiver and is guaranteed to operate at data

rates up to 250kbps. Drivers are short-circuit current lim-

ited and protected against excessive power dissipation

by thermal shutdown circuitry that places the driver out-

puts into a high-impedance state. The receiver input has

a fail-safe feature that guarantees a logic-high receiver

output if the inputs are open, shorted, or connected to a

terminated transmission line with all drivers disabled.

The MAX3158 typically draws 25mA of supply current

when unloaded or when fully loaded with the driver dis-

abled. Supply current drops to 25µA when the device is

placed in shutdown mode. The device is pin selectable

between half- and full-duplex mode and also features

an independently programmable receiver and transmit-

ter output phase through separate pins. The MAX3158

is a low-cost replacement for opto-isolated trans-

ceivers. For fully isolated RS-485/RS-422 transceivers,

refer to the MAX1480 family data sheet.

________________________Applications

Industrial Controls

Telecommunications

Level Translators

Local Area Networks

Features

o ±60V Isolated Data Interface

o +5V Single Supply

o Low-Cost Replacement for Opto-Isolated

Transceivers

o True Fail-Safe Receiver While Maintaining

EIA/TIA-485 Compliance

o Pin-Selectable Full/Half-Duplex Operation

o Phase Controls to Correct for Twisted-Pair

Reversal

o 25µA Low-Power Shutdown Mode

o Thermal Shutdown for Driver Overload Protection

o 28-Pin SSOP Package

o Slew-Rate-Limited Reduced EMI

High CMRR RS-485 Transceiver

with ±60V Isolation

________________________________________________________________ Maxim Integrated Products

1

MAX3158

C1HI C2LO C2HI

C1LO

TXP

RXP

DE

DI

RE

RO

GND

A

B

Y

Z

YR

ZR

AR

BR

MICRO

RT = 100

Ω

0.1

µF

C3

1

µF

C4

10nF

C1

0.047

µF

C2

0.047

µF

±60V

GND OFFSET

ISOCOM

RG

REMOTE GND

RS-485

NODE

H/F

ISOVCC

Typical Operating Circuit

19-2778; Rev 0; 2/03

Ordering Information

Pin Configurations appear at end of data sheet.

PART

TEMP RANGE

PIN-PACKAGE

MAX3158CAI

0

°C to +70°C

28 SSOP

MAX3158CPI

0

°C to +70°C

28 PDIP

MAX3158EAI

-40

°C to +85°C

28 SSOP

MAX3158EPI

-40

°C to +85°C

28 PDIP

For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at

1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.