Issue link: https://iconnect007.uberflip.com/i/1210212
FEBRUARY 2020 I DESIGN007 MAGAZINE 55 only source of interference. Displays, for exam- ple, are also known to interfere. Many devices are in or near the dashboard; if you now have an antenna close by, you get all this interfer- ence in radio or mobile phone reception or 4G communication. Shaughnessy: Sometimes, you still have to use some kind of shield to block the radiation. Löwer: Sometimes, you are forced to do so, but that is usually a sign for bad planning; it's a last-ditch effort. If you try to shield something, then something must have gone wrong in an earlier stage. The best solution is to either pre- vent emitting anything from the start or to emit into non-critical frequency ranges. Therefore, it is important to plan the oper- ating frequencies of power supplies, electric motors, and inverters. That's one of the exam- ples of pre-planning you can do in early project stages. Later on in the project, operating fre- quencies are fixed. You can only work on the mitigation of interference. That reduces possi- bilities and can possibly increase costs. As I said earlier, I am often called into the project once it's too late. Shaughnessy: They have already made design decisions. Löwer: There are different design decisions. Sometimes, it has to do more with the manu- facturing or cost optimization, or issues were not seen beforehand. Other times, the design- er wants to have a specific form or shape. For example, today, nobody wants to have anten- ply with them as well, except for the issue of reading Chinese, and most European EMC en- gineers don't understand Chinese. You have similar situations in consumer products and industrial applications. The number of norms and regulations is quite large, so the first EMC issue I see is, "Which norms do we have to ful- fill?" Shaughnessy: And in America, you have to deal with FCC regulations. Löwer: Yes, but they are pretty straightforward. There are a lot of them, but they don't contain any surprises. You can read them for free on- line, which makes it a lot easier. Everything is open-access, and you can look into it if you like. This is not the case in all regions. I don't see that EMC regulations or problems are get- ting fewer and fewer, but they're changing. I have customers in the automotive indus- try who have lots of issues in their cars. Each car gets more and more electronics, and the trend is not stopping. We already see more is- sues in interference between different systems, such as interoperability between components in the same system becoming more and more EMC-related. Therefore, it gets more and more work. Shaughnessy: Which segment of boards has the worst EMC problems right now: automo- tive or consumer? Löwer: The worst I've seen personally is in au- tomotive. You have a lot of systems that are tightly packed. What I see is that the general regulations, such as FCC, are met, but the cars interfere with themselves, so you get interfer- ence in radio reception, for example. In the U.S. market, you typically have long-ranged AM radio bands in use. That's quite a chal- lenge for switch-mode power supplies. The AM bands are pretty much the same frequency range as the higher-order harmonics of these power supplies. You also have a lot of power supplies in your car. Each device usually has several DC/ DC converters integrated, and they are not the The best solution is to either prevent emitting anything from the start or to emit into non-critical frequency ranges.