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TPS53015: Input/Output capacitor

PAN-M
Mastermind 8375 points
Part Number: TPS53015
Other Parts Discussed in Thread: LM27403

Hi,

The input voltage is 12V, and the output voltage is 5V, please teach me the appropriate value of the input/output capacitor.
The inductor is 10uH.
When the output voltage of EVM is 1.05V, the input capacitors are 10uF+10uF+10uF and the output capacitors are 22uF+22uF.
In the case of the 5V output, how does this value change?

Regards,
PAN-M

  • 0
    TI__Mastermind 23965 points

    For Cout

    See section 8.2.2.2 of the TPS53015 datasheet,  you will need to know or estimate the load step rate and output ripple. 

    Use the max capacitance calculated from the equations 7, 8, and 9.

    For Cin,

    Use a 0.1uF and  10uF high quality ceramic decoupling capacitor near the VIN pins.   Additional, capacitance may be required depending on the rms current and desired ripple voltage.     Use equations 13, 14, and 15 from lm27403 datasheet to estimate the input rms current and ripple voltage.

  • 0 in reply to David_Daniels
    Mastermind 8375 points

    Vin(max)=12V
    Vout=5V
    Lout=10uH
    fSW=500KHz
    IL(ripple)=583mA
    As a result of equation 7; 7.29uF

    delta ILOAD=6
    delta VOS=0.1
    But, result of equation 8 is 90uF

    Results of COUT are different.
    Which is right?

  • 0 in reply to PAN-M
    TI__Genius 14455 points

    Hi,

        Please calculate the capacitance using equation 7 - ripple, equation 8 - over shoot and equation 9 - undershoot. You will have to select the maximum of the 3 value. Add a 20% margin to the capacitance that you have selected.

    Regards,

    Gerold