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TPS74401: Review request: TPS74401RGWR

Preethi T
Prodigy 50 points
Part Number: TPS74401

Hi All,

We have used TPS74401RGWR in our design to power a 3.3V module at 200mA load current.

Please review and provide your feedback ASAP.

Also, please clarify if the output capacitors affects the soft start time

Thanks,

Preethi

TPS74401RGWR_TI.PDF

  • 0
    TI__Guru 50190 points

    Hi Preethi,

    This will work. If you are not using the PG pin it can be either grounded or left floating as it is open-drain. You may want to add a feed-forward capacitor from VOUT to FB as an option. This can help to further reduce PSRR and noise. 

    With respect to soft-start time, both the SS (Soft-Start Capacitor) and COUT will impact the ramp time. This is shown here:

    Does this help to answer your question?

  • 0 in reply to JCHK
    Prodigy 50 points

    Hi,

    Thanks for your quick response.

    We have 58uF load capacitor on the LDO output. (Tsscl ~ 1ms). But we have configured the tss using Css capacitor as 2.41ms. 

     Which one will actually come into picture? Either 1ms or 2.41ms?

    Regards,

    Preethi

  • 0 in reply to Preethi T
    TI__Guru 50190 points

    Hi Preethi,

    The CSS capacitor will dominate the soft-start time. 

    Regards,

  • 0 in reply to JCHK
    Prodigy 50 points

    TPS74401RGWR.PDF

    Hi,

    Thanks for your response.

    Can you please review the layout of this LDO(attached) and provide your valuable comments.

    Note: There are no components in the bottom plane.

    Regards,

    Preethi

  • 0 in reply to Preethi T
    TI__Guru 50190 points

    Hi Preethi,

    This looks OK but if you are not using the PG function, you can simply ground the PG pin as it is an open-drain output. This would allow you to remove R179 and improve the layout a bit.

    I hope this helps.