ISO485 Datasheet, PDF (1/11 Pages) Burr-Brown (TI) – Isolated RS-485 DIFFERENTIAL BUS TRANSCEIVER

®
ISO485
ISO485
Isolated RS-485
DIFFERENTIAL BUS TRANSCEIVER
FEATURES
q RS-485 AND RS-422 COMPATIBLE
q 100% TESTED FOR HIGH-VOLTAGE
BREAKDOWN
q RATED 1500Vrms
q SINGLE-WIDE 24-PIN PLASTIC DIP
q EASY TO USE
q LOW POWER: 180mW typ at 5Mbit/s
APPLICATIONS
q MULTIPOINT DATA TRANSMISSION
ON LONG BUS LINES IN NOISY
ENVIRONMENTS
RE
2
R
1
3 V_SA
DESCRIPTION
The ISO485 differential, isolated bus transceiver uses
Burr-Brown’s capacitively coupled isolation technol-
ogy to provide high-speed, low cost bus isolation.
The ISO485 is designed for bi-directional data com-
munication on multipoint bus transmission lines and
meets EIA Standard RS-485 as well as EIA Standard
RS-422A requirements.
The ISO485 uses high voltage 0.4pF capacitors in-
stead of the LED and photodetector which are used in
equivalent optocoupler solutions. As a consequence
the part count of the isolated RS-485 channel is
reduced from multiple optocoupler channels, an RS-
485 transceiver chip and supporting circuitry to one
ISO485. The capacitors in the ISO485 provide a high
voltage barrier, 1500Vrms and greatly reduce current
spikes on the power line.
The ISO485 combines a 3-state differential line driver
and a differential-input line receiver both of which
operate from a single 5V power supply. The driver
differential outputs and the receiver differential input/
output bus ports are designed to offer minimum load-
ing to the bus whenever the driver is disabled or
V_S = 0V.
15 V_SB
A ₁₂
B ₁₃
D
24
DE
23
22
GND
A
11
14
GND
B
TRUTH TABLE
RS-485
DE RE
BUS
00
01
R_X
HIGH Z
1 0 HIGH Z
11
T_X
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Tel: [phone] • Twx: 910-952-1111 • Cable: BBRCORP • Telex: 066-6491 • FAX: [phone] • Immediate Product Info: [phone]
©1994 Burr-Brown Corporation
PDS-1280C
Printed in U.S.A. May, 1995