UCC28063A: UCC28063A question about interleaving operation,master and slave were not 180 ° shifted waveforms.

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Replies: 8

Views: 99

Part Number: UCC28063A

Dear support member,

My customer created board using UCC28063A.

When we confirmed the interleaving operation,Master and slave were not 180 ° shifted waveforms.

The waveform was out of the interleave operation as shown below.

(Question)

Q1.What can be considered?

Q2.What is the cause?


Best regard.
Bob Lee.

8 Replies

  • HI Bob,

    I will look into this and get back to you.

    Best Regards,

    Ben Lough

  • In reply to Benjamin Lough:

    Hi Bob,

    Could you send me a schematic for this design? I would like to review it.

    Best Regards,

    Ben  Lough

  • In reply to Benjamin Lough:

    Hi Bob,

    Along with the schematic could you also ask your customer to probe the inductor currents in each phase? It would be good to understand if both phases are still achieving transition mode operation or perhaps one phase is going into DCM while the other is not. Perhaps one of the ZCD signals is getting corrupting and throwing off the timing.

    Best Regards,

    Ben Lough

  • In reply to Benjamin Lough:

    Dear Benjamin Lough,

    Thank you very much for reply.

    I attached file of schematic.
    Could you check it?


    My customer is measuring inductor current.
    I will send you as soon as the waveform arrives.


    Best regard.
    Bob Lee.

    UCC28063A_Question_190910.pdf

  • In reply to Bob Lee62837:

    Dear Benjamin Lough,

    Thank you very much for reply.


    I attached file about schematic and waveform.
    Could you check it?

    Best regard.
    Bob Lee.

    UCC28063A_Question_Waveform_190910.pdf

  • In reply to Bob Lee62837:

    Hi Bob,

    What I would suggest is go ahead and install a 22pF capacitor between ZCDA and gnd and also between ZCDB and gnd. Check if the behavior improves. I would also suggest checking to see if the probe is impacting the switching timing when a probe is connected to either ZCDA or ZCDB. Try looking at the combined input current with no probes on either ZCD pins and also look at the combined input current when only 1 probe is connected to either ZCDA or ZCDB. Lastly, I would suggest trying to reduce the TSET resistance and see if the interleaving improves.

    Best Regards,

    Ben Lough

  • In reply to Benjamin Lough:

    Dear Benjamin Lough,

    Thank you very much for your answer.

    I reply my customer your answer.
    I will feedback my customer situation.


    Best regard.
    Bob Lee.

  • In reply to Bob Lee62837:

    Thanks Bob,

    Let me know how things look after the changes.

    Best Regards,

    Ben Lough