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WEBENCH® Tools/TPS55340: Cin of aluminium capacitor

K.Hamamoto
Guru 12155 points
Part Number: TPS55340

Tool/software: WEBENCH® Design Tools

Hi

I simulated TPS55340 with the following condition by WEBENCH.
As the results, the Cin was selected a alminium capacitor such as 22uF(ESR:1.2ohm).
Can we use the alminium capacitor such a high ESR for Cin if the Vin_ripple is accepted for the application?

Vin=24V(+/-10%)
Vout=32V
Io=0.5A 

Regards,

Koji Hamamoto

  • 0
    TI__Prodigy 540 points

    Hi Koji,

           Thank you for using WEBENCH, and bringing this issue to our attention. We are currently looking into this and will get back to you once the issue is resolved.

    Thanks,

    Hadi

  • 0
    TI__Prodigy 540 points

    Hi Koji,

         

           The Cin_ESR upper limit was set to achieve an input voltage ripple not exceeding 3% of the Vin. The max allowed ESR is determined by the input current ripple through the Cin, and as you lower the load current, you may observe selected Cin with larger ESR value. So, from input voltage ripple perspective, the ESR value is acceptable. However, it is preferred to have lower Cin_ESR for better efficiency performance (though the impact might not be significant for light-load situations ...). In the new version, I added some additional limitting factor to keep the ESR value low enough even under ligh-load conditions. The latest code is now on the production server. Please create the design and let me know your feedback.

    Thanks,

    Hadi

  • 0 in reply to Hadi Ebrahimi
    Guru 12155 points
    Hi Hadi-san

    Thank you ! I understood.

    Regards,
    Koji Hamamoto