UCC28631: UCC28631

Hello, Jan:

Thanks for your asking. Let me clarify this situation. 

1. A flyback converter which used UCC28631 does not work. There is no output after you plug in the input voltage. 

2. It is found that the start-up voltage of N4, VDD(PIN6) I guess, and there is no signal output on DRV(PIN5). 

3. After you replaced N4 with a new UCC28631, the output could be generated and everything is normal. 

 According to the description, yes, it seems the old one is possibly defected.

Did you ever put the old one back to N4 to check it again?  It is helped to check if this issue is caused by soldering. Or you could measure the resistance of each PIN between the suspect IC and good one. It may talk some clue that which pin is defected. It is helpful to check if there is any potential factor to cause this defect. 

 I am not sure what support you need now because it seems the non-start up issue was solved by IC replacement. 

If you need component level failure analysis support, you may contact the local TI window for component level analysis. 

Regards, 

Wesley 

Just for explanation ....

At the moment, we have many failures on Texas Instrument components. We deal a lot with sellers (Arrow, Awnet, Mouser)

Unfortunately, Mouser told me....you have to post a problem via the discussion on the forum, where TI tech will respond to customer issues
as soon as the component is declared unsuccessful, the customer must send us a forum link to the answer ..

The whole problem is described in detail in the failure test report which i have sent to Mouser Electronics Inc

The answer to your questions

Did you ever put the old one back to N4 to check it again? It is helped to check if this issue is caused by soldering.
Yes, we performed crosscheck with the component N4 and the result is the same - the component N4 is a defective. The soldering defect is ruled out.

Hi, Jan:

I am trying to figure out how to support you for your situation. We use E2E to support technique issues. However, in your case, it seems you already found the the non-startup issue is caused by defected IC... and sorry I do not have the report. Is there anything I could do for you?

Hi, Wesley

Thank you for your cooperation!

Yes you can do so .... Contact Ms. Bogar with Mouser Electronick Inc. and request some information regarding this complaint.

This complaint under number 250008511 (Katek Czech Republick) was officially sent to Mouser Electronick Inc and it has already been assigned RMA number s / o 689468 inv 61363200

Unfortunately, this claim has still not been made to Texas Instrument until you have confirmed that it is indeed a damaged component.

Did you understand my request?

Hi, Jan:

Now I understand your request. However, E2E is for technical discussion, such as waveforms..bugs.... We do not really handle RMA. 

Let me check how does it work and give you reply soon. 

Hi, Jan:

The information I got is, the process should be as below.

it need customer to send Failure part to TI through their contact window with TI. 

According to your description, the DRV has no signal even VCC reaches start-up voltage, and the system can operate normally after only IC replacement. I thought this information is enough to identify it would be something wrong of the suspect IC.  

It would be good if you could share some waveform that you measure before. i.e, the original IC vs. new IC to check the phenomenon you mentioned. 

I thought this post would be okay to your contact window to move forward to next step of  failure analysis process. 

Thanks. 

Wesley

Hi, Jan:

You may get mis-understand. E2E does not handle this failure analysis. E2E only is only used to discuss technical/design issues. i.e. waveform checking, design suggestions, solution suggestions and circuit optimization...etc. So what I did is just confirm it might be something wrong of the suspect IC according to your description. Please discuss with your contact window to ask further support such as RMA, failure analysis...etc if you need.

Thanks

Regards,

Wesley