RS485 isolator with capacitive coupling — what it is and where it fits
The MAX14942GWE+ is a 3-channel, unidirectional RS485 digital isolator from Analog Devices using capacitive coupling technology. It is designed to provide galvanic isolation up to 5000Vrms between an RS485 bus transceiver and the host-side logic, making it suitable for industrial fieldbus interfaces, motor drives, PLC I/O modules, and medical equipment where noise immunity and safety isolation are required. The part supports a data rate of 20Mbps, which covers standard RS485 baud rates up to Profibus and high-speed Modbus RTU links.
Timing and transient immunity
Maximum propagation delay is 68ns in both directions, with typical rise/fall times of 15ns. This timing budget is tight enough for 20Mbps signaling but should be checked against your bus timing margin, especially in daisy-chained multi-drop networks. Common-mode transient immunity is rated at a minimum of 35kV/µs (typical), which is important for maintaining data integrity in environments with fast-switching power stages like motor drives or inverters.