PCB Board Layout Is Critical When The Power Supply And MCU Live On The Same Board
by Kevin Parmenter, Chair, and James Spangler, Co-chair, PSMA Safety and Compliance Committee , How2Power Today, Feb 16 2018
Focus:
In many simple industrial and consumer products there is printed circuit board (PCB) that
contains both a microcontroller (MCU) and a simple off-line power supply. When there is a
failure in EMC testing, the customer’s first reaction is often to blame the power supply. But
very likely, it is a poor PCB layout that caused the data lines to radiate. After reviewing
some of the basic requirements of PCB design, this article goes step-by-step through the
details of layout of a PCB for an MCU. Scans of radiated EMI for the example MCU application
demonstrate how the errors in pc board layout led to compliance failures. The article also
discusses what to do when there is no ground plane; some power-supply related layout problems
and how to address them with resistors and decoupling capacitors; and the need to consider
manufacturing requirements early in pc board design process.
What you’ll learn:
- How to prevent and solve EMI problems in microcontroller applications with power supplies on board
- How to lay out a PCB with MCU and power supply on board to achieve low EMI
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