Feature: Electronic design


Figure 1: Magnetic field of a closed current loop


PCB layout techniques for eliminating EMI in LED driver circuits


By Selim Borekci, Nihal C. Acar, Alper Candir and Halil I. Aytekin, Akdeniz University, Turkey


P


ower electronic circuits convert voltage and current to match the needs of loads. Converters usually have two stages – control and power – and must be highly efficient, low cost and small. Instead of linear supplies, applications such as motor control, lighting,


automotive and renewable energy typically call for switching- mode power converters.


18 March 2022 www.electronicsworld.co.uk


Figure 2: Long current return path with a small cross-section


Figure 3: Green mask (left) and copper layer (right) scheme of the project’s LED driver PCB


Te building blocks of converters are normally capacitors, inductors and semiconductor switches and their drivers. To ensure high efficiency and compact size, circuits are operated at higher switching frequencies, which can cause higher switching losses and unwanted electromagnetic interference (EMI) between PCB traces, components and ground. Hence, a main issue when designing power circuits is to prevent EMI. Due to standards and CE certification requirements, many


power electronic applications also call for EMI filters, which tend to increase circuit size and cost. This challenge becomes even more important in low-power circuits, requiring careful


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