Isolated RS485 transceiver for industrial bus nodes
The MAX14938GWE+ from Maxim Integrated is a 3-channel, unidirectional, capacitively coupled isolated RS485 transceiver. The part delivers a 20Mbps data rate and provides 2750Vrms galvanic isolation between the bus side and the logic side. With a propagation delay of 68ns (max) and rise/fall times of 15ns, the part supports high-speed polling and real-time control loops common in industrial automation and motor-drive feedback links.
The 2750Vrms isolation rating covers basic insulation for 250V working voltage systems. Because the part does not include an integrated isolated DC-DC converter (Isolated Power: No), the bus-side 5V rail must be supplied externally — either from a separate isolated supply or from a bus-powered scheme. This is a design consideration: the BOM needs a small isolated DC-DC module or a transformer-coupled flyback if the system does not already have an isolated 5V rail on the field side.
The 16-SOIC wide-body package (0.295-inch width) provides adequate creepage for the isolation voltage in high-humidity or condensing environments.