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Original question:

TPS7H4010-SEP: TPS7H4010 Output Capacitor Specifications

TPS7H4010-SEP: Minimum Cout

Anthony Flores
Prodigy 110 points

Part Number: TPS7H4010-SEP

Tool/software:

What happens when the output capacitance is below the minimum Cout equation?

  • 0
    TI__Genius 9091 points

    Anthony,

    If you are referring to equation (28) in the device datasheet, then selecting COUT below the calculated value may result in not meeting the load step requirement input to the equation. This is driven by the system requirements the device is being placed in.

    While not directly related to equation (28), COUT also controls the device's loop bandwidth. Therefore, using a very small amount of COUT may degrade stability margins. Equation (18) can be used to estimate the loop bandwidth based on VOUT and COUT.

    Thanks,

    Andy

  • 0 in reply to Andy Fondaw
    Prodigy 110 points

    Yes equation (28), thank you. Does that equation still apply when operating in DCM or PFM? Or how would those modes affect the output capacitance equation?

  • +1 in reply to Anthony Flores
    TI__Genius 9091 points

    Hi Anthony,

    I believe equation (28) should still be valid when the device is operating in PFM mode (and therefore DCM) as the control loop should still respond in the same duration. Although there may be some differences.

    It is also important to note that equation (28) is meant to be used as a starting point for component selection and other calculations, and implementation specifics and load-step characteristics not accounted for in equation (28) will cause variations in performance.

    Thanks,

    Andy