Datasheet

ADM2682E/ADM2687E Data Sheet
Rev. C | Page 20 of 24
TYPICAL APPLICATIONS
An example application of the ADM2682E/ADM2687E for a full-
duplex RS-485 node is shown in the circuit diagram of Figure 45.
Refer to the PCB Layout section for the recommended placement
of the capacitors shown in this circuit diagram. Placement of
the R
T
termination resistors depends on the location of the node
and the network configuration. Refer to AN-960 Application Note,
RS-485/RS-422 Circuit Implementation Guide, for guidance on
termination.
Figure 46 and Figure 47 show typical applications of the
ADM2682E/ADM2687E in half duplex and full duplex RS-485
network configurations. Up to 256 transceivers can be connected to
the RS-485 bus. To minimize reflections, terminate the line at
the receiving end in its characteristic impedance and keep stub
lengths off the main line as short as possible. For half-duplex
operation, this means that both ends of the line must be terminated
because either end can be the receiving end.
ADM2682E/ADM2687E
TxD
A
B
Y
Z
DE
RxD
RE
ISOLATION
BARRIER
TRANSCEIVER
GND
1
GND
1
GND
2
ENCODE
ENCODE
ENCODE
DECODE
DECODE
DECODE
D
R
OSCILLATOR
RECTIFIER
REGULATOR
V
ISOOUT
V
CC
V
CC
V
ISOIN
MICROCONTROLLER
AND UART
R
T
3.3V/5V POWER
SUPPLY
100nF 10µF 100nF 10nF
100nF 10µF
100nF 10nF
DIGITAL ISOLATION i Coupler
iso Power DC-TO-DC CONVERTER
09927-124
Figure 45. Example Circuit Diagram Using the ADM2682E/ADM2687E
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