This topic is discussed in detail in the following blog post - Designing Input Isolated 2-Wire Sensor Transmitters (Part 5) .
There is also some discussion of input isolation in the next video of the Precision Labs series, both in terms of…
1. PWM frequency is 16 kHz, but lower frequencies as low as 4 kHz has been tested as well.
2. Most measurements were done with AWG as source, when MCU was used as a source, 16 MHz clock frequency is used.
3. Details about the circuit…