Avian’s Blog

Yesterday I was invited to give a presentation at a seminar on procedures for product certification. My former colleagues at the Department of Communication Systems at the Jožef Stefan Institute invited three companies to share their experiences in getting electronics products to European market. We discussed compliance with the CE mark, testing for safety and electromagnetic compatibility standards and various other approvals that are required before you can put mass-produced electronics on the shelves.

In my presentation (slides are here) I've discussed my view of the two certification cycles I've participated in at Klevio during roughly the last year and a half. I did a short intro about the company and products and then listed what we chose to certify and how. I didn't do any general intro into the certification procedures and individual measurements. This in the end turned out just fine, because others did it better than I could. Most of the time I spent talking about purely practical lessons we learned on how to best prepare for the task. Looking back at it now, I feel like most of my advice boils down to having a good understanding of what is involved and not basing your expectations purely on certification lab's sales pitches.

I wasn't sure how much time I would have and what the interest of the audience was. Because of that I've put the details on debugging specific compliance problems into a separate part of the presentation. I've ended up doing that part of the talk as well. I discussed a problem we had with an ESD test temporarily disabling an audio codec IC and a problem with radiated emissions that took 3 months to debug and led to some pretty significant changes to one of the DC-DC converters.

I wanted to talk more about some interesting home-brew methods of estimating radiated emissions. I spent a lot of time researching and experimenting with them when I was debugging Klevio's compliance problems. In the end I realized that I could spend a whole talk just on that topic. It also turned out that none of those methods were actually useful in finding a solution, so it didn't make much sense to do more than just list them out. For more info on that, here's an article I found useful on making magnetic loop probes. The idea for the common-mode current probe based on a ferrite ring is from the Application Note AN045 by Richtek. The SDR-based method was my own idea based on my previous research on spectrum sensing and I might eventually do a longer write up on that in the future.

In the end, it was interesting to compare notes and what others have learned solving similar problems. I found that even though our EMI problem took longer to solve than others presented at the seminar, Klevio's experience didn't differ much in regard to timelines or certification lab practicalities. It seems almost everyone stumbles upon some problems during certifications, and while specific issues are unique, the biggest obstacle to finding a solution seems pretty universal: reproducing the problem outside of the certification lab.