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UCC27714EVM-551: UCC27714EVM 600W Ref Design Question

Cao Cao
Intellectual 770 points
Part Number: UCC27714EVM-551

Hi Sir,

Currently we simulated UCC27714EVM-551 600W Phase Shifted Full Bridge Converter Evaluation Module has power sequecncy issue, need you help.

May I know follow as below power sequency is right? if yes, will lose soft start effect?
1. Second side VCC power on.
2. Primary side VCC power on.
3. Buck Cap DC 420V in.

  • 0
    TI__Intellectual 2910 points
    Cao Cao,

    Thank you for your interest in the UCC27714EVM-551 eval module. Per the its user guide, the EVM was not designed to start up from 0-V input voltage. Please make sure the input voltage is between 370 V and 410 V before applying the bias voltages. Thus, the power sequence you describe is not recommended.

    Please also note that 420V exceeds the max DC input voltage spec for this EVM.

    What kind of issues are you observing?

    - Daniel
  • 0 in reply to Daniel Ruiz
    Intellectual 770 points
    Hi Daniel,

    Because we find start up can burn MOSFET issue on EVM.
    1. Primary side VCC power on. (occur High gate is turn on)
    2. Supply input voltage between 370 V and 410 V.
    3. Second side VCC power on.

    Could you help us to comment right start up step? Thanks.

    Cao Cao
  • 0 in reply to Cao Cao
    TI__Intellectual 2910 points

    Cao Cao,

    Per the EVM user guide, the supply input should be applied prior to the bias voltages.

    Please clarify what sequence is being used when you observe the MOSFET failures. Also, which MOSFET(s) is failing?

    I will also go ahead and contact an expert on the controller IC to get their input.

    Regards,

    - Daniel