Full-Duplex, Low Power,
Slew Rate Limited, EIA RS-485 Transceivers
ADM488/ADM489
FEATURES
FUNCTIONAL BLOCK DIAGRAMS
Meets EIA RS-485 and RS-422 standards
250 kbps data rate
Single 5 V 10% supply
−7 V to +12 V bus common-mode range
12 kΩ input impedance
2 kV EFT protection meets IEC1000-4-4
High EM immunity meets IEC1000-4-3
Reduced slew rate for low EM interference
Short-circuit protection
ADM488
A
R
RO
DI
B
Z
Y
D
Figure 1.
Excellent noise immunity
30 μA supply current
ADM489
A
B
APPLICATIONS
Low power RS-485 and RS-422 systems
DTE-DCE interface
Packet switching
Local area networks
R
RO
RE
DE
DI
Z
Y
D
Data concentration
Data multiplexers
Integrated services digital network (ISDN)
Figure 2.
GENERAL DESCRIPTION
The receiver contains a fail-safe feature that results in a logic
high output state if the inputs are unconnected (floating).
The ADM488 and ADM489 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 Electronics Industries
Association (EIA) RS-485 and RS-422 standards. Both products
contain a single differential line driver and a single differential
line receiver, making them suitable for full-duplex data transfer.
The ADM489 contains an additional receiver and driver enable
control.
The ADM488/ADM489 are fabricated on BiCMOS, an
advanced mixed technology process combining low power
CMOS with fast switching bipolar technology.
The ADM488/ADM489 are fully specified over the industrial
temperature range and are available in PDIP, SOIC, and TSSOP
packages.
The input impedance is 12 kΩ, allowing 32 transceivers to be
connected on the bus.
The ADM488/ADM489 operate from a single 5 V 1ꢀ0 power
supply. Excessive power dissipation 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.
Rev. D
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