This presentation will focus on the fundamental concepts of printed circuit board (PCB) or printed wiring board (PWB) layout for switch mode power supplies. These concepts help deliver successful power supply designs irrespective of power levels and topologies. Also included will be basic layout parameters influencing the performance of the design, how these parameters manifest and how to control them. We will explore EMI, thermal performance and layout examples. This presentation is not only useful for engineers who are performing the PCB layout activities but also those engineers who are involved in reviewing the power supply designs and those who are troubleshooting power supply designs for various issues.