• State
  • Locked Locked
  • Replies 1 reply
  • Subscribers 63 subscribers
  • Views 612 views
  • Users 0 members are here
Support feedback
Options
Options
Related

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.

TPS79401 enable and output behavior

Dan Andersen
Genius 11460 points

My customer is using the TPS79401 in their system.  I can share the schematic in a direct email if needed.

They notice that when they have the regulator running in steady state and they quickly toggle the enable pin (off then on), the device does not immediately begin to rise on re-enable, but instead continues to discharge the output to a certain level and then starts up as normal.  (Vdrive_EN is the enable, VDRIVE is the output):

Why is this happening?

Is there risk of damage to the part if used this way?

Is there a change to the circuit we could make to prevent this from happening?

Thanks,

Dan

  • 0
    TI__Guru 55940 points
    Hi Dan,

    Thanks for the scope shot. I have a few clarifying questions.

    Is the concern only that Vout does not reach zero before returning to a high voltage or is there concern where the voltage flattens out at ~1.225 before continuing to decay?

    How short of enable pulses are expected in your application? Is the 60ms pulse the shortest?

    Are you using an NR capacitor or a feed forward capacitor?

    Very Respectfully,
    Ryan