Digital isolators advantages over traditional optocouplers



What are the advantages of using digital isolators over traditional optocouplers in data transmission applications?

Since an optocoupler uses the light from its LED to transmit data through the isolation barrier, the LED is ON when logic high, and OFF when it is logic low, which causes power consumption during the data transmission.

Due to the faster transfer response of a digital isolator, coding can be used to express the logic high level and logic low level, as shown in the following figure.
Therefore, it can reduce power consumed on data transmission process; it’s also better able to handle complex bidirectional interfaces such as USB and I2C.

In additional, digital isolators have better Common Mode Transient Immunity (CMTI).

  • CMTI is important because high‐slew‐rate (high‐frequency) transients can corrupt data transmission across the isolation barrier. CMTI is commonly measured in kV per microsecond and refers to the ability of an isolator to reject noise that is present between the isolator input and output. High CMTI indicates a robust isolation channel.

Digital isolators can reach 200kV/us, whereas optocouplers are usually specified noticeably lower.

Here’s a few related articles that can help you better understand some of the advantages digital isolators can offer for your design:

ADI article: iCoupler® Digital Isolators Offer Key Benefits Over Optocouplers in Solar PV Inverters

Digital Isolators Offer Improved Performance and Lower Cost Options for Solar PV Inverter Designs