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UCC28064A: Adding a snubber circuit

Hirotsugu Kobayashi
Mastermind 9540 points
Part Number: UCC28064A

Tool/software:

Hi team,

Adding a snubber circuit will change the load that transitions between operating modes (burst, single, dual).

Is it possible to use a snubber circuit?

If so, are there any concerns about using a snubber circuit?

Best regards,

  • 0
    TI__Genius 12795 points

    Do you have the schematic for reference?

  • 0 in reply to Ning Tan
    Mastermind 9540 points

    The schematic is the same as the EVM.

    The snubber is 12 Ω and 330 pF placed between the drain and source of the FET.

    We are investigating the effect of the snubber circuit on the operation of the IC.

    Adding a snubber circuit changes the load at which the mode transition occurs. Is there any problem with this operation?

  • 0 in reply to Hirotsugu Kobayashi
    TI__Genius 12795 points

    There is no snubber circuit in EVM schematic

    Do you mean to add RC on top of the existing EVM schematic?

    Why do you need to do this? EMI?

  • 0 in reply to Ning Tan
    TI__Mastermind 40520 points

    Hello Hirotsugu-san, 

    The addition of R-C snubbers to the MOSFETs will slightly increase the total power loss at the lighter load when the mode transitions should occur.
    As a result the COMP voltage will adjust itself to accomodate the additional loss while keeping Vout regulated.

    This adjustment of COMP voltage will slightly affect the output power levels where the mode transitions are expected to occur. 
    It should be a simple matter of tuning the divider resistor values for PHB and BRST inputs to compensate for the adjusted COMP voltage at those target conditions. 

    Regards,
    Ulrich 

  • 0 in reply to Ulrich Goerke
    Mastermind 9540 points

    Hi Ulrich,

    Thanks for the advice.

    I don't see any examples of snubbers being used in TI's EVM or reference designs, but is it okay to use a snubber?

  • +1 in reply to Hirotsugu Kobayashi
    TI__Mastermind 40520 points

    Hello Hirotsugu-san, 

    Sorry for the delay.  Yes, snubbers may be used with the UCC2806x family of controllers (which includes the UCC28064A) without causing any control issues.   If TI's designs have not used them, it indicates that the designer of the circuit did not feel that a snubber was necessary for that design. 

    Regards,
    Ulrich