Published by the Medical Device Coordination Group (MDCG), the document, MDCG 2021-25 is intended to provide a “legally defendable and pragmatic” position on requirements…

ssues related to electromagnetic compatibility (EMC) are often identified during qualification testing in an accredited EMC test lab which typically occurs late in the product design cycle. Obtaining a cost-effective solution to these EMC issues may be time-consuming, and many EMC labs can be fully booked or have limited availability, have long lead times, or involve significant costs. But inexpensive test equipment and procedures (let’s call them thrifty methods) used for helping to solve these EMC issues outside an EMC lab are very desirable, especially if no in-house EMC facilities are readily available.

There are several excellent resources for troubleshooting methods and building a low-cost EMC toolkit.¹ This article offers some other test equipment options that have different capabilities and which can be even less costly. Although the thrifty method is mainly used to compare results before and after implementing a fix (not meeting a specification limit), with some experience, it can also be used in the pre-qualification development stage early in the design cycle to identify potential issues before formal lab testing. Identifying issues early allows maximum flexibility to experiment and provides sufficient time to make cost-effective changes before a design is frozen and difficult to change.

hen helping clients in the automotive industry with their DC-DC converters to meet the stringent automotive EMC standards, I often find problems that share some common mistakes. For a start, 90% of the EMI issues are associated with a grounding issue. Poor DC link design contributes to poor conducted and radiated emissions. Another commonly seen mistake is a bad choice of switching devices, which often requires adding more filters later in the design process, significantly increasing costs and potentially jeopardizing the project.

When it comes to designing an electromagnetic (EM) compliant product, some planning is crucial to help ensure product performance and keep costs under control. In this article, we offer three recommendations addressing design aspects of DC-DC converters that will make a huge difference in their EMC performance.

If powertrain modules determine the performance of an electric vehicle (EV) [1], DC-DC converters then play an important role in the stability and reliability of an EV. Their primary function is to transfer energy from a source (e.g., battery pack) to systems and devices that consume that energy (all electronics loads, particularly in the low voltage distribution network of a vehicle). Because of this, the safety and functional safety aspects of a DC-DC converter are also critical. Redundancy design can also be seen for fault tolerance purposes.

his is the seventh column in a series devoted to the design, test, and EMC emissions evaluation of 1- and 2-layer PCBs that contain AC/DC and/or DC/DC converters and employ different ground techniques [1-6].

Figure 1 shows the functional blocks of the PCB assembly [1].