• State TI Thinks Resolved
  • Locked Locked
  • Replies 7 replies
  • Answers 3 answers
  • Subscribers 22 subscribers
  • Views 806 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.

TXS0108E: Ringing outputs / Spice Model

Robert Sierk
Prodigy 190 points

Part Number: TXS0108E

Hello,

Wondering if I can get my hands on Spice model for this part.  We are seeing issues where the part occasionally starts ringing and will not stop until the system is powered down.   I'd like to try and implement a spice circuit.  

Regards,

Rob

  • 0
    Guru 325050 points

    Oscillations can happen if the signal lines have ringing that exceeds the edge detection threshold (30 % of VCC as far as I know) and thus trigger the edge accelerators to go into the opposite direction.

    I suspect the signal lines are too long and/or have too much parasitic capacitances/inductances. Can you show the board layout?

  • 0 in reply to Clemens Ladisch
    Prodigy 190 points

    This is a case of ringing that doesn't dissipate until power is removed from the board.

    For instance, an interlock signal was sitting satisfied, we went to do something (turn power on), so no change of state. It went oscillatory and remained that way until we physically took power away from the system.

    It doesn't happen all the time; it is an occasional occurrence.

    This is the A-side (receive side) of the device that goes into oscillations.  The B-side is the drive side or the source side.  A scope probe on the B Side (the signal that was driving it) would help remove the oscillatory rate.

    A is running at 1.8 volts and is tied into an FPGA

    B is running at 3.3 volts and is routed to a board-to-board connector.

    This is a uni-directional signal.

  • 0 in reply to Robert Sierk
    TI__Mastermind 47735 points

    Hey Robert,

    Can we see the scope waveforms you obtained during your debugging? As Clemens has stated, this may be a loading issue. That board-to-board connector may be adding a lot of parasitic capacitance.

  • 0 in reply to Dylan Hubbard
    Prodigy 190 points

    Would you expect the ringing to be self feeding? In other words, the ringing continues indefinitely until we power down the system.   We believe we have an RF coupling issue that could be triggering the RTA's.  Is it possible this disturbance trips the edge rate accelerators causing a self feeding condition that continues to ring until power is removed.

  • 0 in reply to Robert Sierk
    TI__Mastermind 47735 points

    Hi Robert,

    I won't rule out the possibility. Ringing/reflections can definitely these cause auto-direction sensing devices issues. Can I get some more info on this? A schematic and scope shots that you may have taken during the debug process should be sufficient. Especially if you have a shot of normal operation and the issue you are experiencing.

  • 0 in reply to Dylan Hubbard
    Prodigy 190 points

    I can't provide scope shots at this time, unfortunately.  I also can't provide schematic information.  We plan on changing from these parts to a different level translator as we move forward with the next rev of the design.  These parts are a bit unforgiving.

    Thanks for the feedback!!

    Rob

  • 0 in reply to Robert Sierk
    TI__Mastermind 47735 points

    Hi Rob,

    Yes our Auto-bidirectional translators can be finicky due external factors impacting the direction sensing. For unidirectional signals I always recommend a direction controlled device since they are more robust to external parasitics. Please see the FAQ below for our recommendations based on industry communication protocols:

     https://e2e.ti.com/support/logic/f/151/t/740319?tisearch=e2e-sitesearch&keymatch=faq%3Atrue