In this circuit, the LTM2887-3S µModule (micromodule) isolator provides isolated signaling and power to the LTC2876 for a complete, 3.3V robust, galvanically isolated transceiver. LTC2876 is a PROFIBUS RS485 transceiver designed to meet the specifications for PROFIBUS-DP masters and PROFIBUS-DP slaves, fully compatible with IEC 61158-2.
The VCC2 output of the LTM2887-3S provides an isolated 5V supply that can be used to power the LTC2876 and the termination resistors. In this application, VCC2 is connected to a digital return channel on the LTM2887-3S with output on PWR_MON for a convenient way to determine when VCC2 is up. The LTM2887-5S can be used in place of the LTM2887-3S if a 5V input supply is required.
This robust solution provides protection from ESD to ±52kV on the bus pins and ±10kV across the isolation barrier (human body model), both unpowered and powered.