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Original question:

TPS54140: tps54140 startup issue

TPS54140: rated voltage required for the parts

FUJIO OZAWA
Prodigy 10 points
Part Number: TPS54140

How much rated voltage excluding margin do the parts(C or R) connected to the  terminal of SS/TR,  RT/CLK, COMP, BOOT need ?

  • 0
    TI__Mastermind 27030 points

    HI OZAWA:

    if you mean the power stage capacitor and resistor connect to like Vin, SW and Vo, you need consider the voltage derating from your system. we suggest for capacitor, you need consider  capacitance derating by voltage . for the resistor, it higher than 50V will be enough. and make sure the resistor is in its power rating range.

  • +1 in reply to Daniel Li14
    Prodigy 10 points

    Thanks for the answer.

    I saw the User's Guide TPS54140EVM-429 1.5-A, SWIFT. Regulator Evaluation Module
    "">www.tij.co.jp/.../slvu285.pdf .

    The Table 5. TPS54140EVM-429 Bill of Materials on 14 page says C4=25V, C6=25V, C7=10V, C8=50V.

    I want to know why C4=25V, C6=25V, C7=10V, C8=50V.

  • +1 in reply to FUJIO OZAWA
    TI__Mastermind 27030 points

    Hi OZAWA:

    the capacitor voltage rating need higher than the voltage it need, 

    for C4, it need high than SS so all the capacitor above 10V rating are fitting for SS cap.

    same as C6,C7 and C8. 

    it won't necessary to keep same voltage capacitor in the same pin with our EVM, you only need make sure voltage on the capacitors not over their max voltage rating 

    Thanks

  • 0 in reply to Daniel Li14
    Prodigy 10 points

    Hi Mr.Daniel Li14
    Thank you for your advice.
    I understood by your explanation.