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TPS51120: TPS51120 PWM Double pluse issue

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Replies: 6

Views: 101

Part Number: TPS51120

Hi Sir,

Our customer response the TPS51120 have PWM Double pluse issue as below,

We have cut-output not loading affect, we have try to short COMP2 to VFB2 not improve.

How can we improve this problem?

  • Hi Sir,

    Update schematic,

    this issue only on 3.3V power.

  • In reply to Hugo Liu:

    Hi,

    some input for reference.

    1, Check C16 spec whether can meet formula 19 in datasheet.

    2, if item1 is ok, parallel a 20pf cap with R9 to try.

    3, after 1 and 2, the issue still happen, let's review layout.

    And by the way, check this happen only at light loading or both light loading and heavy loading..

    Yuchang

  • In reply to Yuchang Zhang:

    Hi Sir,

    we are parallel a 20pf cap with R9 to try, Not significantly improved.
    But we are change to 100pF Double pulse improved as below picture.
    What's the Cap max value for TPS51120?

    Add 100pF

    Add 20pF

  • In reply to Hugo Liu:

    Hi Sir,

    Does TI have suggest Cap max value for TPS51120?

    Hugo

  • In reply to Hugo Liu:

    Hugo,

    I remembered I answered this question, but seems I failed to submit.

    Generally suggest this cap not over 100pf.

    Yuchang

  • In reply to Yuchang Zhang:

    Hi Sir,

    Thank you very much

    Hugo

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