Functional safety isolation

Hi all,

We're developing a functional safety product in accordance with IEC 61508 and ISO 13849.

In our circuit we have a safety-related processor, using an SPI interface to exchange data with a uC non-functional safety.

According with functional safety standards, this SPI communication must be isolated.

By reading ISO 13849-2 (Safety-related parts of control systems), I found some information about opto-isolators (table D.19), which says that optocoupler must be "built in accordance with overvoltage category III according to IEC 60664-1. If a SELV/PELV power supply is used, pollution degree 2 /overvoltage category II applies". But I haven't found any requirements or recommendation to use digital isolators instead.

We have already cataloged ADuM1402 in our database and we desire to use it. Then comes my question: is ADuM140x suitable for functional safety applications? how AD manages the possible faults on digital isolators?

Many thanks in advance!

  • Hello froliveira,

    The overvoltage category, pollution degree and working voltage will determine the required creepage and clearance for the isolator. This is independant of technology (optocouplers or digital isolator) and will primarily dictate package choice.

    Our digital isolators are used in applications today requiring functional safety, but the products themselves don't implement any specific functions in that regard.