Correct Snubber Power Loss Estimate Saves the Day

Focus:

This article looks at the assumptions behind the formula for resistor power dissipation in an RC snubber (P=CV2f), and then does an analysis to determine the true power dissipation based on actual circuit conditions. A new equation is derived that accounts for the fact that the voltage seen by the snubber is not always a step function. Rather than being a perfect square wave with infinitely fast edges, the switch-node voltage waveform has finite rise and fall times. A case study illustrates the value of the newly derived equation for snubber dissipation. The article also explains under what conditions designers can apply the original, step-function-based formula for resistor power dissipation. Results are verified by performing a SIMPLIS simulation.

What you’ll learn:

• How to determine the actual power dissipation of the resistor in an RC snubber

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Author & Publication:

by Nazzareno (Reno) Rossetti and Rayleigh Lan, Maxim Integrated, San Jose, Calif., How2Power Today, Dec 15 2016

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