PMP30280: Flyback control switch node ringing.

Marc de la Chevrotiere

Prodigy 10 points

Part Number: PMP30280

Tool/software:

Can you tell why there is SSN and/or ringing on the switching node of the flyback controller.

over 1 year ago

0 Robert Taylor1 over 1 year ago

TI__Expert 6670 points

Hi Marc,

This is very normal behavior for a flyback converter. This ringing is due to the leakage inductance of the transformer.

R2, C5, D3, R3 form a RCD Clamp that is used to control the peak of the ringing.

Thanks,

Robert

0 Marc de la Chevrotiere over 1 year ago in reply to Robert Taylor1

Prodigy 10 points

thanks

0 Marc de la Chevrotiere over 1 year ago in reply to Robert Taylor1

Prodigy 10 points

Hi Robert,

Is it possible to filter out a few of the highest harmonics on the switching node above nyquist, to minimize the ringing so as not to contribute to EMI without affecting power output efficiency?

0 Robert Taylor1 over 1 year ago in reply to Marc de la Chevrotiere

TI__Expert 6670 points

Hi Marc,

No it is not possible. Anything that is done to reduce the harmonics or change the frequency of the ringing will affect the efficiency.

Thanks,

Robert

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PMP30280: Flyback control switch node ringing.