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TPS25830A-Q1: The minimum output capacitor value is confirmed.

Alan Xia
Genius 9610 points
Part Number: TPS25830A-Q1

Tool/software:

Hi team，

There is a question that we want to confirm with you:

 

1、Regarding the USB Cout capacitor, in the datasheet it mentioned we need a minimum capacitance of 110uF for 3A. But in the EVM design, there are only 3*22uF capacitance.

So could you please help us to confirm when the inductance is 10uH and the power frequency is 500k, what is the minimum of the capacitance?

  • 0
    TI__Expert 6711 points

    Hi Alan,

    1. The capacitor value can be changed due to the maximum input voltage, load transient and output ripple requirements. The maximum voltage in the EVM is 36 V rather than 18 V in the datasheet application. The load transient and output ripple requirements are not claimed so they can also be different. These could cause the different Cout selections. Additionally, C17 may potentially contribute to the voltage stability. The tolerance percent selection can also be different.

    2. Assuming all other parameters and requirements are the same as the datasheet application and the only differences are L and fsw, the minimum Cout you need is 92 uF with 0.084 Ohm ESR. No margin or tolerance is considered in this calculation.

    Best Regards,

    Ke Wang

  • 0 in reply to Ke Wang
    TI__Genius 9610 points

    Hi Ke，

    One more question, do you have TPS25830 complete EMC test report with your own EVM? Can you share to us?
    We have EMC (RE/CEI/Stripline) failure issue when use 2m type C USB cable connected. Do you have some advice? We plan to change the switching frequency from 2M to 500kHz.

  • 0 in reply to Alan Xia
    TI__Expert 6711 points

    Hi Alan,

    Please refer to PCB Layout and Parameters Recommendation for TPS2583X EMC Performance.

    An EMC failure can be caused be caused by many different reasons. The design itself, the test setup, the floor noise, the sensing unit calibration and so on. You can start a new thread for the EMC test with detailed test setup picture, procedures, results for further discussion if you need.

    BR,

    Ke Wang