Datasheet

MAX3140
SPI/MICROWIRE-Compatible UART with Integrated
True Fail-Safe RS-485/RS-422 Transceivers
28 ______________________________________________________________________________________
120Ω
120Ω
DATA IN
DATA OUT
R
D
RO
RE
DE
DI
A
B
Z
Y
MAX3140
(FULL DUPLEX)
Figure 20. Line Repeater in Full-Duplex Mode
5μs/div
V
A
- V
B
DI
RO
1V/div
5V/div
5V/div
Figure 21. System Differential Voltage at 50kHz Driving 4000
Feet of Cable with SRL = Unconnected
2μs/div
V
A
- V
B
DI
RO
1V/div
5V/div
5V/div
Figure 22. System Differential Voltage at 100kHz Driving 4000
Feet of Cable with SRL = V
CC
1μs/div
V
A
- V
B
DI
RO
1V/div
5V/div
5V/div
Figure 23. System Differential Voltage at 200kHz Driving 4000
Feet of Cable with SRL = GND
Typical Applications
The MAX3140 is designed for bidirectional data com-
munications on multipoint bus transmission lines. The
RS-485 transceiver can be used in any RS-485 applica-
tion due to its numerous features and its programmabili-
ty. A typical half-duplex circuit for the MAX3140 is
shown in Figure 24, and a corresponding half-duplex
network is shown in Figure 25. A typical full-duplex cir-
cuit for the MAX3140 is shown in Figure 26, and a corre-
sponding full-duplex network is shown in Figure 27.
Since the MAX3140’s internal UART has IrDA capability,
a standard IR transceiver (e.g., the MAX3120) can be
used to provide IrDA communication (Figure 28).