The MAX1481/MAX1484/MAX1485/MAX1486 provide
software-selectable, half-/full-duplex, low-power, slew-rate-
limited, and high-speed (12Mbps) RS-485/RS-422
operation in a 10-pin µMAX® package—the smallest
10-pin package available.
The software-selectable, half-/full-duplex MAX1485/MAX1486 make obsolete the normally larger and more
expensive solutions required for selectable half-/full-duplex
RS-485/RS-422 operation: 1) a 14-pin, full-duplex
transceiver configured via jumpers between
receiver and transmitter lines, or 2) two 8-pin, half-duplex
transceivers, which require an additional inverter
logic gate for software selectability.
The MAX1481/MAX1484 are functionally equivalent to
the industry-standard MAX491 and 75180, and are
designed for space-constrained, full-duplex RS-422
applications.
All parts contain one driver and one receiver and feature
a 1/8-unit-load receiver input impedance, allowing
up to 256 transceivers on the bus. The MAX1481/MAX1485 feature reduced-slew-rate drivers that minimize
EMI and reduce reflections caused by improperly
terminated cables, allowing error-free data transmission
up to 250kbps. The MAX1484/MAX1486 driver slew
rates are not limited, allowing them to transmit up to
12Mbps.
The MAX1481/MAX1484/MAX1485/MAX1486 draw only
300µA of supply current. The MAX1481 has a low-power
shutdown mode that reduces supply current to only
0.1µA. All devices operate from a single 5V supply.
Drivers are output short-circuit current limited and are
protected against excessive power dissipation by
thermal-shutdown circuitry that places the driver outputs
into a high-impedance state. The receiver input has a fail-safe
feature that guarantees a logic-high output if the
input is open circuit.
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