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TLV62569: Inductor selection

Johnson Cheah
Intellectual 1300 points
Part Number: TLV62569

Hi Team,

I see TLV62569EVM is using high SRF frequency (52MHz) of inductor, can customer use 5MHz frequency inductor as attached? Kindly advise. Thanks.

 

lp25cz01.pdf

  • 0
    TI__Expert 3465 points

    Hello Johnson,

    I'm happy to help you. My advice would be to always use high SRF inductors. At this link:

    you can find a detailed explanation of the inductor's complete model. Anyway, below I've reported the main picture we need for the explanation of the two reasons why you should make this choice:

    -We need the inductor to behave inductively at the switching frequency (1.5 MHz circa) and for the above harmonics, so that the inductor current has a triangular waveform character. An SRF of 52 MHz will ensure it until the 34th harmonics circa.  An SRF of 5 MHz will make the inductor act like a resonator, enhancing the 3rd and 4th harmonics, and kill the others, which will bring to stability and losses problems.

    -the higher the SRF the less the HF noise is coupled to the output, hence less conducted EMI on Vout.