Introduction
Layout design in switching converters is a critical aspect that directly influences the electrical, thermal, and electromagnetic performance of the system. Poor component placement or current path routing can cause instability, unwanted emissions, and difficulties in product certification.
This article presents a compilation of best practices focused on buck topologies, applicable both to prototypes and mass-production products. The recommendations are intended for electronic engineers seeking to maximize efficiency and robustness in their designs right from the PCB stage.
Design recommendations for MPS Buck MP9942
1. Inductor orientation
Always orient the inductor’s reference point (pin 1) toward the SW pin of the IC (in this case, pin 3) to reduce electromagnetic noise emission and improve performance in electromagnetic compatibility (EMC) testing.
2. Optimal LC filtering
In LC filtering, place the MLCCs immediately after the inductor to minimize triangular currents. This reduces output ripple (I_ripple) (~5.28mm).
3. Short switching paths
Keep the path between the SW pin and the inductor as short as possible to minimize high-frequency loops. The shorter the high-frequency loop, the lower the radiation and associated ringing issues (~4.75mm).
4. Input loop in buck topology
In buck topologies, the input loop must be considered critical. Place MLCCs as close as possible to the VIN pin. Minimizing the input loop (~2.58mm) reduces conducted EMI issues.
5. Copper-free area under the inductor
To avoid the generation of Eddy (Foucault) currents, it is essential to keep the area directly beneath the inductor free of copper. This minimizes heating losses and improves overall system efficiency. In this case, we extend the copper-free area to the end of the PCB since there is no GND on either the top or bottom layers.
6. Ground plane compactness
Finally, a compact GND plane distribution is key to ensuring efficient return paths, low impedance, and proper thermal dissipation. Fragmented planes or long return paths that may act as antennas should be avoided.
Conclusion
Success in switching converter design does not rely solely on component selection but also on careful layout implementation. Applying these practices not only helps comply with demanding EMC standards but also improves thermal stability and system durability. These recommendations provide a solid foundation for developing efficient, robust solutions ready for demanding industrial environments.
Support during design and prototyping phases
At Eurotronix, we understand that design success does not end with theory. That’s why we provide our customers with a team of specialized Product Managers and FAEs, offering technical support at every stage of development — from component selection to layout optimization and final validation.
If you are interested in diving deeper into the design of this MPS regulator, contact our technical team for support in all project phases:
- Schematic design
- Inductor selection
- Layout optimization following the recommendations described in this article
In addition, for engineers who want to integrate the MP9942 into their projects, we provide evaluation boards that facilitate prototyping and help reduce development time.
Our commitment is to support engineers in designing more reliable and efficient solutions, providing not only high-quality products but also the knowledge and experience needed to successfully tackle any project.
Author
Néstor Galera
Electronic compontents Field Application Engineer
