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Original question:

TPS65133: Chip Explodes 50% of the time on start up

TPS65133: Chip smoking on startup

Paul Warmenhoven
Prodigy 50 points
Part Number: TPS65133

Hello,

I believe that I'm experiencing a similar problem with the TPS65133 exploding on start up 50% of the time and we also suspect an assembly issue related to the ground pad although we are speculating at this point. Do you know what the resolution of this thread was after it was moved to email communication? 

Thanks,

Paul

  • 0
    TI__Mastermind 18550 points

    Hello Paul,

    Thank you for your post.  I am busy with other support issues ahead of this but will look into this and get back to you by tomorrow.

    Kind Regards,

    Liaqat

  • 0 in reply to Liaqat Khan
    TI__Mastermind 18550 points

    Hello Paul,

    Thank you for your patience as I am just getting back to this. You did not link any other thread in your explanation but I think I know which thread you intended to reference. In that thread, there was no damage to the TPS65133 device and I was not able to duplicate customers scenario in my lab. In case of your issue, it is possible that device damage is being caused by board assembly issues or some issue with the design itself. If you can attach a copy of your schematics, I can review to see if I can spot something that may be causing the damage from design perspective.

    Kind Regards,

    Liaqat

  • 0 in reply to Liaqat Khan
    Prodigy 50 points

    Hi Liaqat,

    I would prefer to not send the schematics yet due to confidentiality concerns.

    Investigating further one potential scenario we believe could have happened is the input voltage to this IC experiencing voltage in excess of the 6V rated maximum (likely in the 10V range) but only for a brief period(nS to uS range), not steady state. Can you offer any insight into how you would expect this part to fail in this overvoltage scenario? We are seeing the part act as a short or near short between the voltage input and ground. We verified this with a thermal camera and the part is heating up significantly to the point of failure

    If we were to pull one of the parts off that has failed would it be possible to send back to you for failure analysis?

    Thanks,

    Paul

  • 0 in reply to Paul Warmenhoven
    TI__Mastermind 18550 points

    Hi Paul,

    6V is the absolute maximum for input supply voltage and it is likely that this is what caused the device damage. With Vin higher than 6V, it is possible that internal FETs get excessive drain current due to drain-source breakdown because of overvoltage. There is thermal shutdown that protects the die in case of excessive power dissipation in the device during normal operation but that thermal shutdown works by disabling the converter operation. Over voltage at input is different because disabling the converter will not remove this condition and therefore thermal shutdown can not protect the device in this input overvoltage case.

    Kind Regards,

    Liaqat

  • 0 in reply to Liaqat Khan
    Prodigy 50 points

    Liaqat,

    Thanks for the explanation. If this is the case and the internal FET(s) are breaking down then the input voltage would essentially be shorted to VPOS, right? If that happens then is the converter trying to actively discharge VPOS and that is what is causing the converter to heat up? It looks like the converter actively discharges VPOS to ground when the converter is disabled. 

    Thanks,

    Paul

  • 0 in reply to Paul Warmenhoven
    TI__Mastermind 18550 points

    Hi Paul,

    This device does have active discharge for the outputs but, unfortunately, I do not have enough internal details of the device to be certain of how it may fail when absolute maximum rating of the device is exceeded.

    Kind Regards,

    Liaqat