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DC-DC Converter Output Ripple

by Steve Butler, VP of Engineering, VPT Inc., YouTube, Sep 09 2009

Focus:
VPT, a manufacturer of dc-dc converter modules for high-rel applications, has produced this 7-min video explaining the origins and characteristics of dc-dc converter output ripple as well as techniques customers can use for reducing this ripple. To begin, the presenter uses a whiteboard to describe how the forward and flyback topologies used in VPT’s dc-dc converters produce output ripple. He notes the various components that make up output ripple (and noise) including differential versus common-mode components and high-frequency switching components. He explains that VPT’s inclusion of a filter in its converters typically reduces their output ripple to approx. 20 to 50 mV pp. If further ripple attenuation is required, the company recommends adding a low-ESR output capacitor, and then an L-C filter or common-mode filter if still more attenuation is needed. Tips on connection of remote sense lines, selection of a filter’s corner frequency and Q are given. Finally, the presenter demonstrates how to measure a converter’s output ripple and noise on the bench and the effect of adding the low ESR cap.

What you’ll learn:

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