MAX3291ESD

Overview

The MAX3291ESD 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, allows up to 128 transceivers on the bus via 1/4-unit-load impedance, and includes short-circuit current limiting. It is housed in a 14-pin SOIC package and specified for an operating temperature range of 0°C to +70°C.

Feature Summary

• Driver preemphasis circuitry extends reliable communication distance and increases data rate by reducing intersymbol interference caused by long cables.
• Fail-safe receiver input guarantees a logic-high output if the differential input terminals are left open.
• Low-current shutdown mode significantly reduces power consumption when the device is not actively transmitting or receiving.
• Integrated driver output short-circuit current limiting protects the device against excessive power dissipation during fault conditions.

Applications

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

Procurement Notes

Verify the specific suffix 'ESD' corresponds to the commercial temperature grade (0°C to +70°C) and SOIC package variant required for your design. Confirm that the ordering information matches the exact pinout and electrical specifications listed in the official datasheet before finalizing procurement orders.

Selection Notes

Select this component when designing for high-speed serial communication over extended cable lengths where signal integrity is critical. The integrated preemphasis feature specifically addresses inter-symbol interference, making it suitable for applications requiring data rates between 5Mbps and 10Mbps without external equalization components.

Part Context

This part belongs to the MAX3291/MAX3292 family of high-speed RS-485/RS-422 transceivers. The MAX3291 variant features a fixed internal preemphasis interval optimized for 5Mbps to 10Mbps operation, whereas the MAX3292 offers programmable preemphasis via an external resistor.

Replacement Considerations

The datasheet lists the following parts as pin-compatible alternatives: ’75180, MAX489, MAX491, MAX3080, MAX3083, MAX3086, and MAX1482. Verify that substitute devices support the required data rates and preemphasis functionality if applicable.

FAQ

How does the MAX3291 handle inter-symbol interference?

It utilizes driver preemphasis circuitry which 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 a single bus?

The device features 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.