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  • TI Thinks Resolved

TPS51116: Change ceramic capacitors

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Part Number: TPS51116

Hi,
On TPS51116PWPR, When injecting lower frequency noise than switching frequency, is these lower noise passed to output side through TPS51116?   Or due to switching operation, does not it appear at output voltage?

As a background, my customer is currently using this power supply IC on our board, and he would like to change the output Ceramic capacitor because of cost down. However, the frequency characteristics of the capacitor will be worse at low frequencies than before the change, so he is concerned about whether the product will be adversely affected. The final decision will be confirmed on the actual board, but he wants to confirm whether it is something you should be concerned about.

Thanks and best regards,
M.HATTORI.

  • Hi Hattori-san,

    Changing output capacitor to ceramic itself will not inject low frequency. However, DCAP mode control does need high ESR ripple, which in normal case will need high ESR capacitor. There is a way to add the emulated ESR ripple to feedback. Please look at the below link for more details. You will need RCC circuit across inductor to generate the desired Vout ripple.

    Regards,

    Weidong

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