DS36C278 Datasheet, PDF (1/10 Pages) National Semiconductor (TI) – Low Power Multipoint EIA-RS-485 Transceiver

July 1998
DS36C278
Low Power Multipoint EIA-RS-485 Transceiver
General Description
The DS36C278 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 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_CC is specified at
500 µA maximum.
The driver and receiver outputs feature TRI-STATE^® capa-
bility. The driver outputs operate over the entire common
mode range of −7V to +12V. Bus contention or fault situa-
tions that cause excessive power dissipation within the de-
vice 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)
The DS36C278T is fully specified over the industrial tem-
perature range (−40˚C to +85˚C).
Features
n 100% RS-485 compliant
— Guaranteed RS-485 device interoperation
n Low power CMOS design: I_CC 500 µA max
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)
n ¹â„4 unit load (DS36C278): ≥128 nodes
n ¹â„2 unit load (DS36C278T): ≥64 nodes
n ESD (human body model): ≥2 kV
n Drop in replacement for:
— LTC485, MAX485, DS75176, DS3695
Connection Diagram
01204001
Order Number DS36C278TM, DS36C278TN,
DS36C278M, DS36C278N
See NS Package Number M08A or N08E
Truth Table
DRIVER SECTION
RE*
DE
DI
DO/RI
X
H
H
H
X
H
L
L
X
L
X
Z
RECEIVER SECTION
RE*
DE
RI-RI*
L
L
≥+0.2V
L
L
≤−0.2V
H
L
X
L
L
OPEN (Note 1)
Note 1: Non-terminated, open input only
TRI-STATE^® is a registered trademark of National Semiconductor Corporation.
© 2004 National Semiconductor Corporation DS012040
DO*/RI*
L
H
Z
RO
H
L
Z
H
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