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UCC2897A: schematic check

GARETH OU
Mastermind 9825 points
Part Number: UCC2897A

Tool/software:

Hi

Could you help check the below UCC2897 schematic and any need to adjust

In addition, customers will have to verify EMI Please help to review Ucc2897A circuit design. Whether the line can be reserved or the EMI protection line can be enhanced

ucc2897.pdf

  • 0
    TI__Guru 54055 points

    Hi,

    The schematics review needs about 1 week. Alternatively, please compare your design to the EVM, then ask particular questions where you feel not certain - this can help shorten the review time.

    what do you mean EMI protection line? Where is it in your circuit?

  • 0 in reply to Hong Huang
    TI__Guru 54055 points

    Hi,

    - I am seeing any EMI function in your circuit. Also not understanding what you mean "whether the line can be reserved of the EMI protection can be enhanced". Your circuit does not seem have any EMI function.

    -  REDL (R37) value too low, you need to increase its value to about 20k, at the initial design.

    - C8 (clamping capacitor) value is too small, Usually that capacitor value should be somewhere between 33nF to 100nF.

    - C18 too small, usually 0.22uF should be used.

    - VIN pin if not used, should be open. What is VCC function. D13 and D14 will keep VCC = VIn - 2 diode VF. Not sure what you try to do

    - Suggest R16 = 2k

    - BIAS is not available until soft start close to complete. Not clear during soft start is it enough energy to drive MOSFETs Q8 and Q15.

  • 0 in reply to Hong Huang
    Mastermind 9825 points

    Hi Hong Huang

    Thanks for your comment

    Because customers need to test EMI Are there any recommended solutions that need to be reserved in the circuit?

  • 0 in reply to GARETH OU
    TI__Guru 54055 points

    Hi,

    Usually at the converter input, there should be EMI filter, with one differential mode choke, one common mode choke, each choke follows an X-capacitor. Also there should Y-capacitor between the primary side ground and secondary side ground. The transformer core needs grounded.