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TPS56A37: SMP controller Shorting Issue – Possible ESD Vulnerability?

jakob jeppesen
Prodigy 10 points
Part Number: TPS56A37

Tool/software:

I’m using the TPS56A37RPAR SMP controller to generate power for servos in a project. (Datasheet: link)

However, I’ve encountered an issue where the controller tends to internally short Vin to GND. This has only happened when the system was de-energized, usually while soldering other components onto the board. Given the circumstances, ESD seems like a possible cause, but I’m not entirely sure.

Has anyone experienced similar issues with this part? Is there any known vulnerability to ESD, or could there be another underlying cause?

Additionally, is generating power for servos a common use case for this controller? Any advice on best practices for operation and reliability would be greatly appreciated!

Thanks in advance!

  • 0
    TI__Genius 11305 points

    Hello,

    Typically we do not see random shorts from VIN to GND. A couple things to check here is the soldering when soldering components, keep it isolated from the IC. Also please check the pad when soldering the IC, ensure the pins are not shorted. ESD can certainly cause shorts and unexpected operations. I have not seen issues such as this, specifically for this device. Most ICs are susceptible to ESD.

    I do not see a potential issue with TPS56A37 powering a servo. As long as the conditions are within recommended threshold for this part. The datasheet and User Guide contain good practice for schematics and layouts. They offer the recommended operating conditions etc. You can also share the schematic here and I can review it as well.

    Hope this helps.

    If this helped answer your question, please don't forget to click "This resolved my issue". If not, please reply to this thread.

    Thank you,

    Calan

  • 0 in reply to Calan Elaya
    Prodigy 10 points

    we get the controller (TPS56A37RPAR) soldered from PCBway and we know they work from the manufactury. the problem is that we dont get all parts soldered and we hand solder thouse, it is in the proces of solding these unrelated parts that the part sometimes short. we know it shorts internaly because we test them when we remove them and its only the pads on the part that is shorted not the onse on the PCB. i have attached our schematics 

  • 0 in reply to jakob jeppesen
    TI__Genius 11305 points

    Hi,

    Can you elaborate on which components are occasionally shorting the device when you solder them on? Are they in the schematic you attached?

    Thanks,

    Calan

  • 0 in reply to Calan Elaya
    Prodigy 10 points

    it is the SMP controller part number:  TPS56A37, IC2 in the schematic. it is specifically pads 8,11,12 and 13 that short internally to pads 9 and 3. i know its the controller that does it because we have de-soldered it and found continuity between the pads on the IC but not on the PCB.

  • 0 in reply to jakob jeppesen
    TI__Genius 11305 points

    Hello,

    Can you share the layout file? I would like to take a deeper look to ensure there are no layout issues. From my understanding, when you solder the part, and you solder "unrelated components" around it, it occasionally gets shorted between VIN pins and GND pins correct?

    I would just like to know which "unrelated components" as you stated earlier, are causing TPS56A37 to short.

    Thanks,

    Calan

  • 0 in reply to Calan Elaya
    Prodigy 10 points

    i am unable to upload the KiCAD schematic, i am just getting an error. the unrelated components are LEDs capacitors and resistors other place on the board.

    here is an image of the whole schematic

  • 0 in reply to jakob jeppesen
    TI__Genius 11305 points

    Hello,

    I am currently looking into this and will get back to you.

    Thank you,

    Calan

  • 0 in reply to jakob jeppesen
    TI__Genius 11305 points

    Hello,

    Since VIN and GND are shorting occasionally on some ICs due to unrelated components on the board, please check the VIN to GND impedance on a good unit vs the VIN to GND impedance on a bad unit. Please let me know if they have similar or different impedances. This will help to understand if it is an IC issue or a board issue.

    Thanks,

    Calan