Opto Isolation for I2C

In audio, one of the main concerns is to eliminate any source of noise. The I2C line may be a source of noise as it is connected to a micro controller, LCD and other devices such as an RF remote.

Optocouplers are a standard way to isolate circuits. With I2C, the use of optocoplers is a bit more challenging because the signals are bi-directional. One way to do it is to use an I2C bi-directional buffer and a couple of opto-isolators as shown in this image:



Recently, Analog Devices released a fully integrated solution, the ADUM1250/2250. An 8-pin/16-pin chip solution with transformer-based isolation:



The technology is called "iCoupler Technology" and claims to be superior to pure optical or pure transformer isolation. The following diagram gives an idea on the technology: