[071] Designing Snubbers for Nonisolated Converters

How to design snubbers when you don't know the inductance causing the ringing.

Introduction

This article shows how to design a snubber for circuits where the ringing inductance is not a defined quantity. This applies to nonisolated converters where PCB layout and component leads are responsible for the bulk of the inductance. 

High-Frequency Switching Cell

All power electronics circuits with devices which rapidly turn on and turn off will exhibit voltage ringing when currents are interrupted or initiated. For transformer-isolated designs, the leakage inductance of the transformer usually dominates the ringing inductance, and the first step in snubber design is to measure this inductance value. This process is described in detail in references [1] and [2].

Figure 1: Buck Switching Cell and Circuit Placement