DS36C280

Slew Rate Controlled CMOS EIA-RS-485 Transceiver

General Description

The DS36C280 is a low power differential bus/line trans-

ceiver designed to meet the requirements of RS-485 Stan-

dard for multipoint data transmission. In addition, it is com-

patible with TIA/EIA-422-B.

The slew rate control feature allows the user to set the driver

rise and fall times by using an external resistor. Controlled

edge rates can reduce switching EMI.

The CMOS design offers significant power savings over its

bipolar and ALS counterparts without sacrificing ruggedness

against ESD damage. The device is ideal for use in battery

powered or power conscious applications. I

500 µA maximum.

ity. The driver outputs operate over the entire common mode

range of −7V to +12V. Bus contention or fault situations are

handled by a thermal shutdown circuit, which forces the

driver outputs into the high impedance state.

The receiver incorporates a fail safe circuit which guarantees

a high output state when the inputs are left open (Note 1) .

Features

n 100% RS-485 compliant

— Guaranteed RS-485 device interoperation

n Low power CMOS design:

I

n Adjustable slew rate control

— Minimizes EMI affects

n Built-in power up/down glitch-free circuitry

— Permits live transceiver insertion/displacement

n DIP and SOIC packages available

n Industrial temperature range:

−40˚C to +85˚C

n On-board thermal shutdown circuitry

— Prevents damage to the device in the event of

excessive power dissipation

n Wide common mode range:

−7V to +12V

n Receiver open input fail-safe (Note 1)

≥128 nodes

≥64 nodes

n ESD (human body model):

≥2kV

Connection and Logic Diagram

Truth Table

DRIVER SECTION

DE/RE*

DI

DO/RI

DO*/RI*

HH

H

L

HL

L

H

LX

Z

Z

RECEIVER SECTION

DE/RE*

RI-RI*

RO

L

≥+0.2V

H

L

≤−0.2V

L

HX

Z

L

OPEN (Note 1)

H

Note 1: Non-terminated, Open Inputs only

DS012052-1

Order Number DS36C280TM, DS36C280TN

DS36C280M and DS36C280N

See NS Package Number M08A or N08E

July 1998

© 1999 National Semiconductor Corporation

DS012052

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