Integration, Isolation, and the Secret to Good EMC Design

Integration, Isolation, and the Secret to Good EMC Design

Gone are the days when a single remote could control your television (though maybe you wish it would). Yet even with an ever-expanding menu of new features, better sound quality, and higher-definition video, entertainment systems are getting slimmer, lighter, and more energy efficient. Similarly, consider that in your pocket you have a professional grade camera, a gaming console, and a global network of people and information, all in a single device. Oh, and it makes phone calls too, if you like that sort of thing.

Consumer electronics offer a convenient microcosm for thinking about the big picture, but across industries, today’s innovators are all asking the same question: How can we do more with less?

The answer is integration. When each component does double or triple duty, you don’t need as many of them, so you can fit them into a smaller package. But this increases design complexity and creates new challenges.

Enter Digital Isolation

In industrial, automotive, and renewable energy, different circuits can have different voltage potentials. Failure to isolate these dangerous high voltages can harm people, data, and equipment. Within Analog Devices, my primary role is an EMC engineer within the isolation technology group. We create digital isolation solutions that protect people, sensitive electronic equipment, and data from the harsh environments that they service.

Figure 1: Digital isolation forms a barrier between dangerous voltages and nearby people, data, or equipment that could be harmed by them.

What’s So Hard About Isolation?

While critically necessary, isolation design is also extremely complex. One of the first things they teach in Engineering 101 is to have a solid ground plane—and yet, digital isolation requires you to split the ground plane. When controlled power and data signals are passed across the isolation barrier, it can create EMC issues that can negatively affect electronic systems and networks.

In other words, you have to have isolation, but doing so creates a whole slew of problems.

On top of that, there are many regulations, both local and global, that mandate EMC compliance. These are a set of standards that your design must meet before it can make its way out into the world.

Design for EMC

At the beginning of the design process, there are myriad options for meeting EMC compliance. By the end, there are only a few. You can tack on some ferrite clamps, extra shielding, or some other ad-hoc capacitor, but these last-minute add-ons are a band-aid approach that counteracts all your previous efforts to integrate your solution and quickly get to market.

Figure 2: EMC mitigation techniques that can be implemented by product development phase. [1]

Rather than building EMC compliance onto your product at the end, build it into your product from the very beginning. Anticipate potential EMC problems at the outset. Implement EMC techniques and best practices throughout the design process. A holistic approach to EMC compliance considers end market specifications, PCB layout, and signal integrity—all, of course, within today’s ever-shrinking product footprints.

But most importantly, choosing components and reference designs that have already been tested and proven in the EMC lab is a key step to creating an EMC compliant design. Next time, we’ll dig into component selection and the value of designing in the newest, most cutting-edge components you can get. Be sure to subscribe!

 

[1] Ott, Henry W. Electromagnetic Compatibility Engineering, First Edition. Wiley, 2009.

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