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TS3A5017: Burnt/shorted IC

Ted Richardson
Prodigy 30 points
Part Number: TS3A5017

We built a prototype device that uses 34 of the TS3A5017 IC in the UQFN package. The prototype developed a short between 1S1 (pin 4) and GND (pin 6). We found 3 of theTS3A5017 IC appeared to be burnt on the top of the case above pin 4. They look as if they had an internal short of substantial power. However, the supply to the devices is 3.3VDC with current limited to 25mA. Additionally, the circuit attached to pin 4 is protected by a Semtech SR05 RailClamp. Below is a photo of one of the burnt devices.

I would like to know how this might have happened and how to prevent it.

Thanks, Ted

  • 0
    TI__Mastermind 45495 points
    Ted,

    Do you have a schematic of the prototype board? This is a passive FET switch and would not source or sink current on its own by design. I think we need to look at the type of signals being applied to the device to see if they are within the operating limits of the device.

    The TS3A5017 is rated for 128 mA on the signal path and 100mA through V+ so we would not expect to see this type of effect with currents limited <25mA.

    Have you removed the IC and done curve trace analysis to confirm there is a short between 1S1 and GND or any other pins?

    Have you checked to see if there are any shorts on the PCB?

    Thank you,
    Adam
  • 0 in reply to Adam Torma
    Prodigy 30 points

    Adam,

    Thanks for responding.

    Here is our schematic with the relevant circuits highlighted. Our system is actually an assembly of 3 PCB; Processor board - HRMR400-402, Probe flex - HRMR517-002, and Sensor flex - HRMR514-002.

    We are in the process of checking the Processer board for shorts and current limiting function.

    You requested a "curve trace analysis". I am not familiar with this, can you explain?

    Thanks, Ted

  • 0 in reply to Ted Richardson
    TI__Mastermind 22965 points
    Hi Ted,
    Thanks for sharing the schematics. I did not see anything stand out that would be of concern. As Adam mentioned in his previous post, the issue reported is likely caused by system level fault scenario that might be violating abs-max ratings.

    Does the issue happen at power-up (time-0)or after sustained system use? Is there any difference between how the TS3A5017 devices ares being used (since your reported issue on three out of 34 units).

    Please let us know what you find from your debug of shorts/current limiting function on your processor board.
  • 0 in reply to Ravi Singh
    TI__Mastermind 22965 points
    Ted,
    Just wanted to check if you had a chance to run any debug tests or had any additional questions that we could help with.
  • 0 in reply to Ravi Singh
    Prodigy 30 points

    Ravi,

    We checked the current limiting function of the controller board in question and found it to 27mA into a 100 ohm load, the spec is 25mA. I believe this is acceptable. We are still looking for the source of the failures. We are currently improving the grounding of our fixtures to see if that prevents any further failures. I will let you know if we see any additional failures.

    Thanks, Ted

  • 0 in reply to Ted Richardson
    TI__Mastermind 22965 points
    Ted, Thanks for the update.
  • 0 in reply to Ravi Singh
    TI__Mastermind 45495 points
    Ted,

    We haven't heard from you in a couple of weeks. Do you have resolution to your issue?

    Thank you,
    Adam
  • 0 in reply to Adam Torma
    TI__Mastermind 45495 points
    Ted,

    I am closing this thread due to inactivity. If you have additional questions you may post them here to re-open the thread or start a new one.

    Thank you,
    Adam