• State TI Thinks Resolved
  • Locked Locked
  • Replies 3 replies
  • Answers 1 answer
  • Subscribers 64 subscribers
  • Views 611 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

TPS826711: TPS826711 ripple too high at light load

Nate Enos
Genius 9410 points
Part Number: TPS826711

Hi team,

Posting for a colleague. We are finding that the ripple for the TPS826711 is too high in light load. Is it possible to add some additional output capacitance to reduce this? What's the max we could add before worrying about stability?

Any recommendations on a filter we could use to reduce the ripple?

Thank you for the help,

Nate

  • 0
    TI__Guru*** 142910 points
    Hi Nate,

    The D/S quantifies this on page 6 and discusses this more on page 14.

    Could you share the measured ripple, operating conditions, and ripple target?
  • 0 in reply to Chris Glaser
    Prodigy 20 points

    Sorry for duplicate post- this was previously unreceptive to a reply.

    Chris- Measured ripple does not exceed expected values. Measured ripple is closer to 10mVpp. The issue was late additions to the product specs.

    We'd like to reduce ripple voltage to below 20mVpp from the TPS826711 ideally at Iload > 10mA. We already have had to add additional bulk capacitance to the system totalling 6.9uF for ICs on the supply. We're aware this exceeds the reccomended output capacitance, but would like to know the following:

    What observed instabilities should we expect if the bulk capacitance is too high?
    Other solution ideas for reducing ripple to target.
    Any potentially P2P compatible modules that would help us meet the target
    Thanks-

    Emily Guthrie

  • 0 in reply to Emily Guthrie
    TI__Guru*** 142910 points
    Hi Emily,

    One way to achieve lower ripple is to operate in forced PWM mode. Efficiency will be a bit lower than PFM/PWM mode. Is this ok for your application?

    Instability is most evident during a load step. You might see some ringing in the output voltage.

    There is no pin to pin option. Sometimes a ferrite bead is used to lower ripple. With low load currents, an RC filter may also work.