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Snubber for ADuM447x

Question asked by GarySchneider on Apr 20, 2015
Latest reply on Apr 23, 2015 by GarySchneider

The UG-492 document on the ADuM447x evaluation board on page 4 states "R4, R3, C4, and C5 are provided for an optional and unpopulated snubber, which can be used to reduce radiated emissions." The part seems perfect for my isolated DAQ application and works great in my intended circuit, but the eval board has about 600 mVpp of nasty 20MHz ringing on the ISO GND (P8/P10) with respect to input GND (P2/P4/P6) and will probably kill my CE radiated compliance. Can you provide further guidance on a suggested snubber circuit or design method? I don't know how to estimate either the effective capacitance or inductance for classic snubber design methods.

 

I am using 5V in, +/-5.5V out at 900 kHz with the Halo Electronics TGRAD-560V8LF transformer which fits my physical space.

 

Thanks for all suggestions.

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