UCC2895: Resonant ringing seems excessive. Is this normal?

Michael B

Part Number: UCC2895

Hello - I have a very similar issue - in my case am using UCC28950, but seeing waveforms that nearly match what was posted. What is the primary cause of this and what is typically done to resolve it? Thank you.

over 1 year ago

0 Mike O' over 1 year ago

TI__Guru* 78306 points

Hello,

I am reviewing your inquiry and will get back to you shortly.

Regards,

0 Mike O' over 1 year ago in reply to Mike O'

TI__Guru* 78306 points

Hello,

Could you send me a link and/or waveforms showing the issue?

Regards,

0 Michael B over 1 year ago in reply to Mike O'

Prodigy 20 points

Yes, the waveforms I'm seeing are very similar to what are in the original post: https://e2e.ti.com/support/power-management-group/power-management/f/power-management-forum/591517/ucc2895-resonant-ringing-seems-excessive-is-this-normal

Waveforms:

/cfs-file/__key/communityserver-discussions-components-files/196/tek00251.tif

/cfs-file/__key/communityserver-discussions-components-files/196/tek00245.tif

Thanks!

0 Mike O' over 1 year ago in reply to Michael B

TI__Guru* 78306 points

Hello,

I am reviewing your inquiry and will get back to you shortly.

Regards,

0 Mike O' over 1 year ago in reply to Mike O'

TI__Guru* 78306 points

Hello,

The ringing that you are showing on the transformer is not normal. The following link will bring you to a link with a similar issue and how to resolve it.

https://e2e.ti.com/support/power-management-group/power-management/f/power-management-forum/973624/ucc28950-resonant-current-ringing

Regards,

0 Michael B over 1 year ago in reply to Mike O'

Prodigy 20 points

Thank you - I will try that. Do you think that in my case the snubber is only required on the secondary side even though this abnormality is present on the primary and secondary voltage (and current) waveforms ?

0 Mike O' over 1 year ago in reply to Michael B

TI__Guru* 78306 points

Hello,

I am reviewing your inquiry and will get back to you shortly.

Regards,

0 Mike O' over 1 year ago in reply to Mike O'

TI__Guru* 78306 points

Hello,

The ringing your observing is on the primary of the transformer. The primary of the transformer is coupled to the secondary of the transformer. You should be able to use an RC snubber on the secondary of the transformer to help dampen the ringing. However, you could snub this with a snubber across the primary of the transformer as well.

You could try both to see which one you prefer. I have seen snubbing done on both the primary of the transformer and the secondary so I know both will work.

Regards,

Power management

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UCC2895: Resonant ringing seems excessive. Is this normal?