MAX3291EPD

Overview

The MAX3291EPD is a full-duplex RS-485/RS-422 transceiver manufactured by Analog Devices Inc./Maxim Integrated. It operates from a single +5V supply and features driver preemphasis circuitry to reduce intersymbol interference for high-speed, long-distance communication. The device supports data rates of 5Mbps to 10Mbps and includes a low-current shutdown mode reducing supply current to 100nA. It offers a fail-safe receiver input guaranteeing a logic-high output if the input is open circuit. The receiver input impedance is 1/4-unit-load, allowing up to 128 transceivers on the bus. It is housed in a 14-pin Plastic DIP package with an operating temperature range of -40°C to +85°C.

Feature Summary

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

Applications

• Long-Distance, High-Speed RS-485/RS-422 Communications
• Telecommunications
• Industrial-Control Local Area Networks

Procurement Notes

Verify component authenticity through authorized distributors or direct manufacturer channels. Confirm the specific suffix 'EPD' corresponds to the 14-pin Plastic DIP package and the -40°C to +85°C industrial temperature grade. Check for RoHS compliance status as indicated in official documentation. Ensure the source provides valid traceability for this discontinued or legacy part number.

Selection Notes

Select the MAX3291EPD for applications requiring fixed preemphasis optimized for 5Mbps to 10Mbps data rates. Choose this part over the MAX3292 variant if resistor-programmable preemphasis intervals are not required. Ensure the design utilizes a single +5V supply. Verify that the system requires full-duplex operation and can accommodate the 14-pin PDIP footprint.

Part Context

The MAX3291EPD belongs to the MAX3291/MAX3292 series of high-speed RS-485/RS-422 transceivers. It is pin-compatible with devices such as the SN75180, MAX489, MAX491, MAX3080, MAX3083, MAX3086, and MAX1482. This series is designed to overcome limitations of conventional transceivers by incorporating preemphasis to mitigate intersymbol interference on long cable runs.

Replacement Considerations

Public confirmed substitutes include MAX3292EPD (programmable preemphasis), MAX3291CPD (commercial temperature range), and MAX3291ESD (SOIC package). Pin-compatible alternatives listed in datasheets are SN75180, MAX489, MAX491, MAX3080, MAX3083, MAX3086, and MAX1482.

FAQ

How does the MAX3291EPD reduce intersymbol interference?

It uses driver preemphasis circuitry that increases the signal amplitude at every transition edge for approximately one baud period, counteracting the effects of cable RC time constants.

What is the maximum number of transceivers supported on the bus?

The MAX3291EPD has a 1/4-unit-load receiver input impedance, allowing up to 128 transceivers to be connected in parallel on one 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.