SPI-to-UART bridge for RS232 and RS485 links
The Maxim Integrated MAX3100CEE+T is a UART controller that translates between an SPI host interface and asynchronous serial protocols RS232 or RS485. It handles the framing, baud-rate generation, and line control so the host MCU only needs to read and write bytes over SPI. The 150 µA supply current makes it practical for always-on or battery-backed ports where you do not want to keep a full UART peripheral powered. The ROHS3 compliance is confirmed.