• State TI Thinks Resolved
  • Locked Locked
  • Replies 1 reply
  • Answers 1 answer
  • Subscribers 62 subscribers
  • Views 103 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.

Original question:

TPS3839: Reset signal problem while IC is being exposed to strong light

TPS3839: 850nm light seems to cause random resets

Paolo Baesso
Prodigy 30 points
Part Number: TPS3839

We have a design with a TPS3839 X2SON working close to a 850nm IR source.

We noticed that the RESET line is randomly being pulled low when an IR LED nearby is flashing and there is a reflective surface in front of it, causing the light to bounce back on the IC.
Flashing a high intensity IR torch in front of the IC also causes random resets.

It does not seem to be a EM noise issue, because all the rails and signals are stable when looked on an osciloscope. Also, covering the IC with an IR absorbing putty prevents the resets from occurring.

To me this seems light an undesired photoelectric effect caused by 850nm light of high intensity.

This seems consistent with what was reported in a previous post:
https://e2e.ti.com/support/power-management-group/power-management/f/power-management-forum/580193/tps3839-reset-signal-problem-while-ic-is-being-exposed-to-strong-light?tisearch=e2e-sitesearch&keymatch=TPS3839#



  • 0
    TI__Expert 5860 points

    Hello Paolo,

    The X2SON package is very small so there is not as much packaging material shielding the silicon die compared to larger packages. The package might be thin enough that some of the IR light at that wavelength can penetrate the package to the die. I would suggest shielding the IC from the IR LED. 

    Best,

    Walter