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UCC28251: Output ripple is too large as 500mV

Ruixin Feng
Intellectual 1885 points
Part Number: UCC28251
Other Parts Discussed in Thread: UCC28250EVM-501, UCC28250,

Hi team,

I tested UCC28250EVM-501. Input 40V, output 3.3V, load is 10A. And I found that the ripple can reach to 500mV.  And I found that the ripple is affected by the switching node. Could you pls help with this issue? I have used a short GND to probe.

Thanks!

Rayna

  • 0
    TI__Guru 51065 points

    Hi,

    If UCC28250 EVM original board ripple voltage does not meet the specs based on its user's guide, you would need to make a return process.

    If you changed something such as change UCC28250 to UCC28251, the original board needs to be tuned up. for example, please refer to the below to know what changes needed. For example, it says, the RT would be different.

    Differences Between the UCC28251 and UCC28250 and Evaluation of the UCC28251 in (Rev. A)

  • 0 in reply to Hong Huang
    TI__Intellectual 1885 points

    Hi Huang,

    Sorry for misunderstanding, we tested the UCC28250 on UCC28250EVM-501. We didn't change any part of the EVM. But the ripple is worse than the spec and the result in user guide. Could you pls share how to optimize the ripple? Or any problem lead to the bad ripple? Thanks!

    Rayna

  • 0 in reply to Ruixin Feng
    TI__Guru 51065 points

    Hi,

    There is a ripple measurement TP1, the ripple waveform was measured on TP1. If TP1 still shows high ripple than the user's guide, there maybe somthing wrong either the board components or your oscilloscope. If you can exclude your oscilloscope and no issue your would have to debug the board or send the board back to the vendor through a return process. 

    If you want to debug the board, please realize you may not be able to make return.