Full-Duplex, Low Power,
Slew Rate Limited, EIA RS-485 Transceivers
ADM488A/ADM489A
FEATURES
FUNCTIONAL BLOCK DIAGRAMS
Complies with ANSI TIA/EIA-485-A-1998 and
ISO 8482: 1987(E)
250 kbps data rate
ADM488A
A
R
RO
DI
B
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
Z
Y
D
30 μA supply current
Figure 1. ADM488A
APPLICATIONS
ADM489A
Low power RS-485 and RS-422 systems
DTE-DCE interface
Packet switching
A
B
R
RO
RE
Local area networks
Data concentration
Data multiplexers
DE
DI
Z
Y
D
Integrated services digital network (ISDN)
Figure 2. ADM489A
GENERAL DESCRIPTION
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 circuitry.
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 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 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.
The ADM488A/ADM489A are fully specified over the industrial
temperature range and are available in SOIC and MSOP packages.
Rev. 0
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