MAX3291ESD+T

Overview

The MAX3291ESD+T is a full-duplex RS-485/RS-422 transceiver featuring driver preemphasis to reduce intersymbol interference. It operates from a single +5V supply with a typical no-load current of 3mA and 100nA in shutdown mode. The device supports data rates up to 10Mbps, offers a -7V to +12V common-mode input range, and allows up to 128 transceivers on the bus due to its 1/4-unit-load receiver impedance. It includes short-circuit current limiting and fail-safe inputs. Available in SOIC-14 packages, it functions within an industrial temperature range of -40°C to +85°C.

Feature Summary

• Driver preemphasis circuitry extends reliable communication distance by reducing intersymbol interference caused by long cables.
• Low-current shutdown mode reduces supply current to 100nA for power conservation.
• Fail-safe receiver input guarantees a logic-high output when the input is open circuit.
• 1/4-unit-load receiver input impedance permits connection of up to 128 transceivers on a single bus.

Applications

• Long-distance, high-speed RS-485/RS-422 communications
• Telecommunications systems
• Industrial control local area networks

Procurement Notes

Verify the component against official Analog Devices documentation to confirm pinout compatibility and electrical specifications. Ensure the operating environment remains within the specified voltage and temperature limits. Cross-reference the datasheet revision to validate performance characteristics before final integration into hardware designs.

Selection Notes

Select this component for applications requiring extended cable lengths or higher data rates where standard transceivers suffer from signal degradation. The fixed preemphasis interval suits designs needing industry-standard pin compatibility without external programming components. Verify that the system power supply noise is minimized to ensure preemphasis functionality at lower data rates.

Part Context

This part belongs to the MAX3291/MAX3292 family of high-speed RS-485/RS-422 transceivers. It is designed as a drop-in replacement for legacy devices like the '75180, offering enhanced performance through integrated preemphasis technology. The ESD suffix indicates an extended industrial temperature rating compared to commercial variants.

Replacement Considerations

Pin-compatible replacements include the MAX489, MAX491, MAX3080, MAX3083, MAX3086, and MAX1482. Note that these alternatives may lack the specific preemphasis features of the MAX3291, potentially affecting maximum cable length or data rate capabilities in existing designs.

FAQ

How does the MAX3291 handle inter-symbol interference?

It utilizes driver preemphasis circuitry to increase signal amplitude at transition edges, counteracting the RC time constant effects of long cables and reducing jitter.

What is the receiver input impedance of the MAX3291?

The receiver input impedance is 1/4-unit-load (48kΩ), allowing up to 128 transceivers to be connected on a single communication line.

How is the low-power shutdown mode activated?

Shutdown is initiated by driving the Receiver Enable (RE) pin high and the Driver Enable (DE) pin low simultaneously.