Rainbow Electronics MAX3430 - Manual (Page 11)

MAX3430
±80V Fault-Protected, Fail-Safe,
1/4-Unit Load, +3.3V RS-485 Transceiver
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Applications Information
128 Transceivers on the Bus
The standard RS-485 receiver input impedance is 12k Ω
(one-unit load), and a standard driver can drive up to
32-unit loads. The MAX3430 transceiver 1/4-unit-load
receiver input impedance (48k
Ω) allows up to 128
transceivers connected in parallel on one communica-
tion line. Connect any combination of these devices,
and/or other RS-485 devices, for a maximum of 32 unit
loads to the line.
RS-485 Applications
The MAX3430 transceiver provides bidirectional data
communications on multipoint bus transmission lines.
Figure 10 shows a typical network applications circuit.
The RS-485 standard covers line lengths up to 4000ft.
The signal line must be terminated at both ends in its
characteristic impedance, and stub lengths off the
main line kept as short as possible.
Chip Information
TRANSISTOR COUNT: 300
PROCESS: BiCMOS