Quickly Characterize Switch-Mode Power Supply Designs

Introduction

From laptops to vacuum cleaners, all electrical products have one thing in common: a power supply. Without stable, well-regulated DC power, devices can malfunction. Historically, linear power supplies were the overwhelming choice for powering electrical products. Today, the switch-mode power supply (SMPS) design has become the industry standard. The next generation of SMPS designs will provide increased power efficiency, density, and reliability; reduced thermals and electromagnetic interference; and eventually lower overall cost. To ensure that your SMPS design meets these requirements, it is essential to fully characterize the operation of your design. You can perform most of the required characterization measurements using an oscilloscope.

Use Case Summary

For switching measurement applications, timing delay errors between voltage and current probes may significantly impact power measurements. The reason is that each specific voltage and current probe has a different propagation delay. For accurate power measurements and calculations, it is essential to equalize the time delay between voltage and current probes using a procedure known as “deskewing.” A deskew fixture enables you to drive voltage and current probes with the same pulse signal. The fixture also allows you to probe at the same electrical point. After you deskew your voltage and current probes, you can begin taking more accurate power measurements.

Characterizing SMPS requires a broad range of measurements and is time-consuming when done manually. The measurements include input, switching, output, and frequency response analysis. You can save time and quickly test your SMPS designs by automating power measurements using an oscilloscope equipped with power analysis software.

Solution Overview

The Keysight switch-mode power supply characterization solution enables engineers to quickly perform power measurements with an oscilloscope using differential probes and current probes calibrated first by the deskew fixture. The mixed-signal oscilloscope’s 12.1-inch touch screen provides a wide view of the automated power measurements enabled by the power analysis software package. Measurements for input, switching, output, and frequency response analysis enable engineers to design and select more efficient power supplies. The deskew fixture helps engineers easily deskew the time delay between the high-voltage differential active probe and the high-sensitivity current probe for more accurate measurements.

Learn more at: How to Make the Best Switch-Mode Power Supply Measurements

Summary

• Trends for greater power efficiency, density, and reliability in SMPS designs create additional testing requirements.

• Characterizing SMPS designs requires a broad range of measurements and is timeconsuming when completed manually.

• First deskew the time delay between voltage and current probes for more accurate measurements.

• Automated power analysis oscilloscope software can help you save time testing your SMPS designs.

For more information: Characterize Switch-Mode Power Supply Designs