• State
  • Locked Locked
  • Replies 11 replies
  • Subscribers 64 subscribers
  • Views 282 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.

TPS54616: TPS54616

Joe Matthews
Prodigy 20 points
Part Number: TPS54616
Other Parts Discussed in Thread: TPS62867, TPSM82866A

Seeing a 2% fallout during board testing with the issue being the 3.3v regulator TPS54616 output going to GND. Failure analysis on several devices found the the issue output shorted to GND. (<5 ohms) caused by EOS of the lower FET device. Following datasheet best practice for schematic and board layout. Have looked at signals during testing and nothing out of spec. Any experience with this and what could cause this repeating specific failure mode?  

  • 0
    TI__Guru*** 146780 points

    Hi Joe,

    Your local FAE would be best to assist with debugging this.  Do the failures occur on a prototype or in the field?

    I can double check your design, if you can send the schematic, BOM, and layout via a private conversation (or you can post them here directly).

    How is Vin supplied?  Is it possible there are overshoots at power on or during a transient?

    If these are a prototype and/or soldered by hand, are you sure that the thermal pad is soldered?

    A newer, smaller 6A device would be recommended such as TPSM82866A or TPS62867.

    Thanks,

    Chris

  • 0 in reply to Chris Glaser
    Prodigy 20 points

    Thanks for the support Chris!

    I have no idea how to contact a local FAE?

    Below is our schematic, following datasheet guidelines.

    That also includes layout and thermal pad.

    Vin comes in from a backplane through a connector onto the board with the TPS5416 

    We have been observing some overshoot transients upto 7V.

    Does the lower FET EOS provide insight to what caused the failure? 

  • 0 in reply to Joe Matthews
    TI__Guru*** 146780 points

    Thanks Joe for sending the schematic.  There was no layout file.

    I'll try and check on my side if there is someone local to you.  You might also check with your colleagues for any TI sales or FAE contacts they have had in the past.

    Are you hot-plugging this PCB into a backplane?  This can cause overshoots on Vin.  7V is the limit for these overshoots, before the device could possibly be damaged.  Did you have a waveform of one of these overshoots?

    The EOS just says that an abs max rating was exceeded.  In my experience, this can usually come from Vin overshoot, non-ideal PCB layout, instability, etc.

    Thanks,

    Chris

  • 0
    Prodigy 20 points

    Are you hot-plugging this PCB into a backplane? No

     Did you have a waveform of one of these overshoots? Yes. short transient spikes. (can't

    Does the time length of the transient spikes critical?

    Is it possible you could have short phone call with us to discuss?

    Thanks for your support!

  • 0 in reply to Joe Matthews
    TI__Guru*** 146780 points

    Hi Joe,

    Theoretically, any duration transient (such as ESD) could destroy the device.  I would still like to see a waveform to check, if you have one.  Usually, the duration of any spike during operation would be some usec long at least.

    Is the failure reproduceable?  Did each device fail during the same test, for example?

    Chris

  • 0 in reply to Chris Glaser
    Prodigy 20 points

    The failure cannot be said as reproducible with a 2% fallout.

    Its short ns's but as high as 7.6v.

  • 0 in reply to Joe Matthews
    TI__Guru*** 146780 points

    Thanks for sharing Joe.  This looks ok and is likely switching noise (from this IC or another one) coupling into the probe at its switching frequency.

    Ae you able to share the PCB layout, here or in a private conversation?

    Chris

  • 0 in reply to Chris Glaser
    Prodigy 20 points

    Yes in a private conversation. Can we set up with a live call where I could share views?

  • 0 in reply to Joe Matthews
    TI__Guru*** 146780 points

    Yes, I found your TI sales contact and Jack should be reaching out shortly to work this specific failure case through email with me.

    Thanks,

    Chris

  • 0 in reply to Chris Glaser
    Prodigy 20 points

    Thanks. I have not heard anything from Jack. What number can I reach him at?

    ALso, We have a Failure Analysis Report from TI dated 2/9/2011 FA318930-1 General Dynamics which matches the FA we did internally.

    That signature issue with the lower FET EOS must have a systemic cause.

  • 0 in reply to Joe Matthews
    TI__Guru*** 146780 points

    Hi Joe,

    I reminded Jack to get in touch with you.  I believe he was traveling this week, so he might reach out tomorrow or Monday if he has a free minute.

    I will remind him again tomorrow.

    Chris