MAX22027FAWA+T

Overview

The MAX22027FAWA+T is a compact, isolated half-duplex RS-485/RS-422 transceiver featuring proprietary AutoDirection control. It provides 3.5kVRMS digital galvanic isolation between the UART side and cable side. The device supports data rates up to 0.5Mbps with slew-rate limited drivers to minimize EMI. It operates with VDDA from 1.71V to 5.5V and VDDB from 4.75V to 5.25V. Key electrical parameters include ±10kV HBM ESD protection on driver outputs and receiver inputs, 50kV/μs common-mode transient immunity, and an operating temperature range of -40°C to +85°C.

Feature Summary

• AutoDirection control eliminates the need for separate DE and RE signals by using an internal state machine to manage driver and receiver states based on TXD input and bus voltage.
• Slew-rate limited drivers reduce electromagnetic interference (EMI) and minimize signal reflections caused by improper cable termination.
• Integrated high-level isolation breaks ground loops and handles large potential differences between ports without external components.

Applications

• Utility meters
• Industrial automation equipment
• Programmable logic controllers
• HVAC systems

Procurement Notes

Verify the specific suffix 'T' indicates tape-and-reel packaging when sourcing this component. Confirm that the 'FAWA+' designation corresponds to the wide-body SOIC package variant with lead-free construction. Ensure the ordering information matches the required isolation voltage ratings and regulatory approvals for the target application environment.

Selection Notes

Select the MAX22027FAWA+T over other variants in the family specifically when reduced EMI is critical, as it features slew-rate limited drivers unlike the MAX22026/MAX22028 series. This model is suitable for applications requiring robust communication up to 0.5Mbps across significant ground potential differences while maintaining low noise emissions.

Part Context

This component belongs to the MAX22025-MAX22028F series of isolated transceivers. It shares the same functional block diagram and isolation architecture with siblings like the MAX22025, MAX22026, and MAX22028, differing primarily in driver slew rate characteristics and receiver output behavior during transmission.

Replacement Considerations

Direct replacements within the same family include the MAX22025FAWA+T or MAX22027FAWA+. Note that the MAX22026/MAX22028 variants offer higher speed but lack slew-rate limiting. Cross-vendor equivalents require verification of isolation voltage and pin compatibility.

FAQ

How does the AutoDirection circuitry function?

The AutoDirection circuitry uses an internal state machine that monitors the TXD input and the differential bus voltage (VA-VB). It automatically enables or disables the driver and receiver to maintain the correct bus state without external control signals.

What is the difference between the MAX22027 and MAX22028 receivers?

On the MAX22027, the receiver output always follows the differential bus voltage (VA-VB). In contrast, on the MAX22026, the receiver output does not follow (VA-VB) when the device is in the driver-enabled state.

What ESD protection levels are provided?

The driver outputs and receiver inputs are protected against ±10kV electrostatic discharge to GNDB on the cable side, specified by the Human Body Model (HBM).