Power Supply Design Seminar (PSDS)

Survey of resonant converter topologies

Starting with 2- and 3-element resonant topology fundamentals, this session walks through the key characteristics, analysismethodology, control challenges and design considerations of resonant topologies. Three design examples demonstrate resonant topology performance with high switching frequency (~1 MHz) or with wide output voltage regulation range (2-to-1 output voltage regulation level). This session also introduces a new resonant topology structure, the CLL resonant converter, with size and efficiency advantages over the traditional LLC  series resonant converter. Finally, this session provides guidance on how to select the best resonant topology for various applications.

Power Factor Correction (PFC) circuit basics

From laptop adapters to power tools, any application powered from the AC grid represents a complex load where the input current is not always in phase with the instantaneous line voltage. As such, the application consumes both real power as well as reactive power from the grid. The ratio between real, usable power (measured in watts) and the total real-plus-reactive power is known as the power factor. A power factor correction (PFC) circuit intentionally shapes the input current to be in phase with the instantaneous line voltage and inimizes the total apparent power consumed. While this is advantageous to utility companies, a PFC circuit also provides benefits in end applications. This topic presents these benefits, how the PFC circuit can impact the AC-to-DC power-conversion architecture, common PFC circuit types, the benefits/disadvantages of different approaches and a PFC solution selection process based on application priorities.

Power-conversion techniques for complying with automotive emissions requirement

This topic addresses the unique challenges of designing power converters to pass automotive EMC requirements based on CISPR 25 requirements, including background information on  the CISPR 25 standard and test setups. We explain common noise sources in power converters and various techniques to reduce conducted and radiated emissions, including input filter design, frequency selection, mode selection, snubber design, shielding and layout. Measured results from a 13.5 V input to a 3.3 V, 5 A output converter case study demonstrate the relative effectiveness of electromagnetic interference (EMI) mitigation techniques and the path to passing CISPR 25 Class 5 conducted emissions.

Switch-mode power converter compensation made easy

Engineers have been designing switch-mode power converters for some time now. If you’re new to the design field or you don’t compensate converters all the time, compensation  requires some research to do correctly. This session will break the procedure down into a step-by-step process that you can follow. We will explain the theory of compensation and why it  is necessary, examine various power stages, and show how to determine where to place the poles and zeros of the compensation network to compensate a power converter. We will  examine typical error amplifiers as well as transconductance amplifiers to see how each affects the control loop and work through a number of topologies/examples so that power  engineers have a quick reference when they need to compensate a power converter.

Constructing your power supply - Layout considerations

Laying out a power supply design is crucial for its proper operation and there are many issues to consider when translating a schematic into a physical product. This topic addresses  methods to keep circuit parasitic components from degrading the operation of your designs. We will discuss techniques to minimize the impact of parasitic inductance and capacitance  of filter components and printed circuit board (PCB) traces, as well as a description of the impact that PCB trace resistance can have on power supply regulation and current capacity. A  general overview of thermal design is also included as well as sample temperature rise calculations in a natural and forced-air environment. Finally, we will review some practical  examples of power stage and control device layouts.