Topology Twists And Circuit Tricks Improve Performance Of Multi-Output Converters

Focus:

SEPIC, Ćuk, Zeta, flyback and inverting buck-boost converters are some of the most common “go-to” topologies when the buck and boost cannot quite do what is needed. After allowing for turns ratios and voltage inversion, they are all governed by the same relationship between voltage and duty cycle. While there are many useful variations for producing one output, the group is particularly well-suited for generating two or more outputs. The author has been working with these converters for many years, and in the process has developed some topology variations and techniques that can improve performance. This 25-page article describes some common and some less-well-known multiple-output buck-boost topologies, providing complete converter schematics, bills of materials and measured performance. These converters take advantage of three circuit tricks that improve their stability or improve cross regulation. The application of these tricks and why they work is explained. This article is intended for engineers with some power conversion experience. It is not intended to provide a complete design manual or a complete method for choosing or designing a power conversion topology. However, the information provided here may affect a designer's choice of topologies by showing ways to gain significant performance improvement.

What you’ll learn:

• How to improve the stability of multi-output buck boost converters
• How to improve the cross regulation of multi-output buck boost converters

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Author & Publication:

Bob Zwicker, Analog Devices, Olympia, Wash, How2Power Today, Sep 15 2014

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