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TPS63700: higher inductance to reduce ripple currrent

Toshiaki Morita
Intellectual 1872 points
Part Number: TPS63700

Tool/software:

Hi team,

The custoemr designed the same as the typical application on datasheet but try to change inductance to reduce ripple current as following. Do you have any concen about that ? 

Vin = 5V, Vout = -5V, Iout = 30mA rms.

L : 22uH (4.7uF in datasheet)

C : 4.7uF(22uF in datasheet)

Regards,

Morita

  • 0
    TI__Guru 58641 points

    Hi Morita,

    The engineer is out of office. Please expect a reply till Tuesday.

    Best Regards,

    Stefan

  • 0 in reply to Stefan Schauer
    TI__Expert 8795 points

    Hi Morita,

    This type of changes are equivalent for only buck converters. Bigger inductance and smaller capacitor will increase Vout ripple and decrease the phase margin. I've calculated the RHP zero and it looks safe with 30mA load, but I'm not sure about customer's requirement for Vout ripple. Usually current ripple is not important for light load device so please check with customer why they need to sacrifice Vout ripple for smaller inductor current ripple.

    Best Regards,

    Travis

  • 0 in reply to Travis Wang
    TI__Intellectual 1872 points

    Hi Travis,

    I've posted this thread without understanding their question and my explanation is wrong, I'm so sorry about that.

    The average current is very low so they'll reduce inductance to oparate CCM. This is reason why they'd decrease the inductance.


    Regards,

    Morita