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TPS54231: Can a capacitor over 27nF be used for Css placed between SS and GND terminal?

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Replies: 6

Views: 106

Part Number: TPS54231

 Hello guys,

 One of my customers is evaluating TPS54231 on their own PCB for their new products. They want to increase Css (softstart capacitor) to over 27nF to avoid TPS54231 input voltage dropping. But the device datasheet says "The slow-start time should be set between 1 ms to 10 ms to ensure good startup behavior. The value of the slow-start capacitor should not exceed 27 nF." on page 11.

 Can a capacitor over 27nF be used for Css placed between SS and GND terminal? For example, can 33nF, 47nF or 100nF(0.1uF) be used as Css? If over 27nF capacitor is not good to use, what kind of problem will be happened?

 Your reply would be appreciated.

 Best regards,

 Kazuya Nakai.    

  • Hi,

    There is no issue for larger Css.

    Shawn

  • In reply to Shawn Nie:

    Hi Shawn,

    Thank you for the prompt reply. I understood over 27nF capacitor can be used for Css.

    By the way do you know what the sentence was discribed for? Is it a misunderstanding of datasheet author?

    Thank you again and best regards,
    Kazuya Nakai.
  • In reply to Kazuya Nakai54:

    Hi,

    This is an old device, I don't know the history, but we have tried larger Css, there is no issue.

    Shawn

  • In reply to Shawn Nie:

    Hi Shawn,

    Thank you for your reply.

    For just reference, could you please tell me what the maximum capacitance value you have tried is?

    Thank you again and best regards,
    Kazuya Nakai.
  • In reply to Kazuya Nakai54:

    Hi,

    We tried 0.1uF, there is no issue.

    Shawn
  • In reply to Shawn Nie:

    Hi Shawn,

    Thank you for the information.

    Best regards,
    Kazuya Nakai.

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