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UCC29002: Demo Board PMP10099RevB not working properly

Part Number: UCC29002
Other Parts Discussed in Thread: PMP10099,

We have built up the PMP10099 according to the TI schematic and Gerbers.
The flybacks all work properly as supposed, unfortunately, as soon as more than one path is active, I can see a very low frequency variation in current of the parts involved, ranging from close to zero to complete current provided by one path all allone. I have 4 of the 8 soldered up.
In the schematic, there is a note which says that R12, R18 are for test purpose only. Taking out R12 doesn't help, taking out both cuts open the FB loop.

I am running out of options...

Regards,

Markus

  • Hello,

    I am sorry that you are having issues with the PMP10009 reference design.

    I am just curious did you modify the design to support your own fly back converters?

    Regards,

  • Hello,

    thanks for your reply.

    No, I did not modify the PM10099. I took all the recommended parts, as long as there were exact ones mentioned, for all the others, I took appropriate ones.

    Can you tell me what to do with these R12 and R18 0R resistors? Taking them both out doesn't make any sense to me.

    What bothers me most is the fact that the 1st and the 2nd path seem to work properly, 3 and 4 - sometimes - show this inaporpriate behaviour.

    Regard,

    Markus

  • Hello,

    First I would trouble shoot the flyback converters to make sure they are operating correctly.  Once that is complete I would verify the compensation components around the UCC29002 are selected correctly.  You can do that with the excel design tool link.

    After you try that if you are still having issues, let me know and I will contact the designer of the reference design so he can help you trouble shoot this design.

    Regards,

  • Hello,

    thank you for the support. I tried my best to play with the .xls, and with measuring, changing parts, in particular the compensation networks, I started to wonder whether the Reao (R17_x) should possibly be 2.74k instead of 2.74R. This value is much closer to the corresponding values in the sheet you provided with the standard values. So I inserted these 2k74 resistors for all 4 paths. Up till now, it seams to run properly.

    Can you verify this one value if there is a faulty value given for the resistors R17?

    Regards,

    Markus

  • Hello,

    It seems that the excel tool gave you the correct value and it seems to be working.

    I think, you should be fine.  If you have any further issues, please let us  know?

    Regards,