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UC3845A: UC3845

Adarsh Kumar
Prodigy 100 points
Part Number: UC3845A

Dear Sir, 

I design a buck converter Input-40-90V, Output 12V,10A.

I used a Input capacitor 220uF 100V , I face a problem  during testing at Input-84V, Output 12V,10A. that the input capacitor is degraded.

why this happned,

pls suggest the solution.

Thanks

  • 0
    TI__Expert 8550 points

    Hello Adarsh,

    Thank you for your question. Can you please elaborate on what you mean by the capacitor degrading at Vin = 84V? Do you have any schematics to help us understand your problem? The UC3845A should be able to handle your specifications as long your converter is designed correctly.

    Regards,

    Jonathan W

  • 0 in reply to Jonathan Wong
    TI__Expert 7900 points

    Hello Adarsh,

    A 220uF, 100V capacitor is likely an electrolytic.

    Here I used Power Stage Designer at 84Vin, 12Vo, 10Ao to estimate the capacitor RMS current

    The input capacitor must support at least 3.6A RMS.  Check the components datasheet, inexpensive capacitors may only support 100s of mA.  Sometimes you need more than 1 capacitor in parallel.

    Regards,

    Eric