MAX1481/MAX1484/MAX1485/MAX1486
Software-Selectable, Half-/Full-Duplex, Slew-Rate-Limited,
12Mbps, RS-485/RS-422 Transceivers in µMAX Package
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Line Length vs. Data Rate
The RS-485/RS-422 standard covers line lengths up to
4000 feet. For line lengths greater than 4000 feet, use
the repeater application shown in Figure 16.
Figures 17 and 18 show the system differential voltage
for the parts driving 4000 feet of 26AWG twisted-pair
wire into 120Ω loads.
Typical Applications
The MAX1485/MAX1486 are designed for bidirectional
data communications on multipoint bus transmission
lines. Figures 19 and 20 show typical network applica-
tions circuits. These parts can also be used as line
repeaters with cable lengths longer than 4000 feet
(Figure 16).
To minimize reflections, terminate the line at both ends
in its characteristic impedance, and keep stub lengths
off the main line as short as possible. The slew-rate-lim-
ited MAX1481/MAX1485 are more tolerant of imperfect
termination than the MAX1484/MAX1486.