an I2C isolation solution from Analog Devices, app note can be found here.
The Inter-Integrated Circuit (I2C®) bus is a two-wire bidirectional bus used for low speed, short-distance communication between integrated circuits. Developed by Philips 1980 in the early 1980s for use amongst ICs on a single board, I2C today is increasingly being used in multiboard applications as new bus extensions and control devices help overcome the original 400 pF maximum allowable load capacitance.
This application note provides a brief overview of the I2C bus (focusing on its physical layer), discusses the challenges in isolating I2C interfaces, and describes iCoupler® solutions for isolating I2C interfaces.