• State Resolved
  • Locked Locked
  • Replies 1 reply
  • Subscribers 63 subscribers
  • Views 360 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.

TPS61222 stability with supercapacitor on output

Dan-o
Intellectual 895 points
Other Parts Discussed in Thread: TPS61222, TPS61220

I have a circuit still in design which uses a TPS61222. CIN = 10uF, L = 10uH, COUT = 10U, with an additional 47mF supercapacitor on the output. The main purpose of this circuit is to charge a supercap for backup supply. There will be no load other than the supercap when the TPS61222 is first enabled. The supercap is 47mF with an ESR of 120 ohm.

There's two things I am worried about:

1) The datasheet doesn't mention a soft start time. I'm figuring since the supercap is 120 ohm I won't have a bad inrush problem.

2) stability - I know some DC DC converters compensation network can be dependent on the output capacitance. Will this be a problem with the TPS61222?

  • 0
    TI__Guru**** 150950 points

    Yes, your 120 Ohm ESR should limit the inrush into the super cap.  Note that the TPS61220 passes Vin to Vout even when the part is off, so without this ESR the IC would be driving a short (charging the supercap) for a long time.

    The TPS61220 should be stable with nearly any output cap.  However, I have not seen a super cap with that much ESR and we don't have any that big in our lab.  So, I recommend that you test it out on the EVM.