UCC28634: Not work properly and difficulty finding the source of the error code

Flavio Caruso

Prodigy 10 points

Part Number: UCC28634

Basic device not working properly.

The project was conceived by the Webench power design tool and I am not able to get it to start working correctly.

As it has several fault protections I'm having a lot of difficulty in diagnosing the problem.

Apparently it is in auto-restart mode. I try to find what fault case code but I´m not have success.

I need some guidance on how to diagnose the cause of the problem.

Could you help me?

3005.WBDesign2.pdf

over 2 years ago

0 Andrew Plummer over 2 years ago

TI__Intellectual 1195 points

Hello Flavio,

Thanks for posting this question and for your interest in designing with UCC28634.

Our team is reviewing your schematic and will provide some feedback within the next 24 hours.

Can you share simulations or waveforms showing VDD, CS and DRV? This will help us identify which fault protection is being triggered.

Regards,

Andrew

0 Flavio Caruso over 2 years ago in reply to Andrew Plummer

Prodigy 10 points

Dear Andrew,

See bellow:

VDD only...

0 Mike O' over 2 years ago in reply to Flavio Caruso

TI__Guru 72115 points

Hello,

The most common issue with primary side regulated (PSR) flyback converters is aux winding and CS noise triggering and OVP or OCP fault. I can see from your waveforms that VDD and CS is quite noisy and more than likely the aux winding is noisy as well. This can generally be solved with an RCD clamp, snubber across the output rectifier and/or a filter capacitor on the CS pin.

The following link will bring you link on PSR fault sensing describing how it works, the most common issues and how to resolve them.

This application note gives instructions no how to setup the RCD clamp, snubber and CS filtering.

https://www.ti.com/lit/pdf/sluaac5

Regards,

0 Flavio Caruso over 2 years ago in reply to Mike O'

Prodigy 10 points

Hello Mike,

Thank you for the document. I will need to read carrifully and try it. I will back soon with the answer!.

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UCC28634: Not work properly and difficulty finding the source of the error code