ANALOG DEVICES ADM488A Service Manual
Full-Duplex, Low Power,
ADM488A/ADM489A
ADM488A
R
D
RO
DI
A
B
Z
Y
08498-001
ADM489A
R
D
RO
DI
A
B
Z
Y
DE
RE
08498-002
Slew Rate Limited, EIA RS-485 Transceivers
FEATURES
Complies with ANSI TIA/EIA-485-A-1998 and
ISO 8482: 1987(E)
250 kbps data rate
Single 5 V ± 10% supply
−7 V to +12 V bus common-mode range
Connect up to 32 nodes on the bus
Reduced slew rate for low EM interference
Short-circuit protection
30 µA supply current
APPLICATIONS
Low power RS-485 and RS-422 systems
DTE-DCE interface
Packet switching
Local area networks
Data concentration
Data multiplexers
Integrated services digital network (ISDN)
GENERAL DESCRIPTION
The ADM488A and ADM489A are low power, differential line
transceivers suitable for communication on multipoint bus
transmission lines. They are intended for balanced data
transmission and comply with both RS-485 and RS-422
standards of the Electronics Industries Association (EIA). Both
products contain a single differential line driver and a single
differential line receiver, making them suitable for full-duplex
data transfer. The ADM489A contains an additional receiver
and driver enable control.
The input impedance is 12 kΩ, allowing 32 transceivers to be
connected on the bus. The ADM488A/ADM489A operate from
a single 5 V ± 10% power supply.
FUNCTIONAL BLOCK DIAGRAMS
Figure 1. ADM488A
Figure 2. ADM489A
Excessive power dissipation that is caused by bus contention or
output shorting is prevented by a thermal shutdown circuit. This
feature forces the driver output into a high impedance state if,
during fault conditions, a significant temperature increase is
detected in the internal driver circ u itr y.
The receiver contains a fail-safe feature that results in a logic
high output state if the inputs are unconnected (floating).
The ADM488A/ADM489A are fabricated on BiCMOS, an
advanced mixed technology process combining low power
CMOS with fast switching bipolar technology.
The ADM488A/ADM489A are fully specified over the industrial
temperature range and are available in SOIC and MSOP packages.
Rev. A
Information furnished by Analog Devices is believed to be accurate and reliable. However, no
responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other
rights of third parties that may result from its use. Specifications subject to change without notice. No
license is granted by implication or otherwise under any patent or patent rights of Analog Devices.
Trademarks and registered trademarks are the property of their respective owners.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781.329.4700
Fax: 781.461.3113 ©2009-2010 Analog Devices, Inc. All rights reserved.
www.analog.com
Loading...