• State TI Thinks Resolved
  • Locked Locked
  • Replies 1 reply
  • Answers 1 answer
  • Subscribers 63 subscribers
  • Views 233 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.

TPS65131: Problem for negative output swing

Satoshi
Guru 19645 points
Part Number: TPS65131

TPS65131 is evaluating 24Vin to ±15Vout, negative out put is swing on startup timing.

Waveform is attached below, time of swing to stable are random: below are 310msec to 2.4sec, right end is zoomed waveform.

※ch1: 5V input, ch2:  -15V output, ch3: -5V output (-15V → LDO → -5V)

When add 51.1kΩ resistor next to feed forward capacitor, swing was disappear and stable.

If there the other idea for noise reduction (without 51.1kΩ), please let me know.

Second question, when Cout increase 44μF to 66μF (without 51.1kΩ), startup timing occur high voltage one swing.

Is this reason also coupling noise and effect loop response, correct?

When occur the other reason, please let me know.

By the way, positive 15V output is stable.

Best regards,

Satoshi

  • 0
    TI__Mastermind 18550 points

    Hello Satoshi-san,

    Both of the scenarios described above seem to be related to noise coupling into FBN pin through feed forward capacitor and our suggested solution is what you have already implemented i.e. add series resistor with feed forward capacitor to limit its bandwidth. I am not aware of any other reason for this behavior.

    Kind Regards,

    Liaqat