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Thread: Teensy 4.0 fried - posting project schematic to make sure I didn't do anything wrong

  1. #1

    Teensy 4.0 fried - posting project schematic to make sure I didn't do anything wrong


    My teensy has gone to the great recycler. I think I might have accidently touched one of the u controller pins with a 9V source, but I wanted to make sure that there is nothing in the circuit design that might have caused this. I am posting the schematic in the hopes that someone will give it a quick look over and let me know if something looks wrong.

    Note that the circuit worked as intended the first time, but not the second time, and between the two I did disconnect and then reconnect the 9V source.

    Thanks for your help!
    Attached Files Attached Files

  2. #2
    Senior Member fdaniels's Avatar
    Join Date
    Oct 2020
    Ostwestfalen, Germany
    Not that i am a pro in electronics, but shoudnt the batteries GND be somehow connected to the Teensys GND?

  3. #3
    You are correct!

    However, the error was on the schematic only. The circuit itself did contain a common ground for the 3v AND 9v power supplies.

    I've included a new schematic to fix the mistake.

    Good catch
    Attached Files Attached Files

  4. #4
    Senior Member
    Join Date
    Jul 2014
    Cordoba, Argentina
    I am guessing you did not read the data sheet for the DRV 8837. The schematic your posted shows this to be true.
    Please reread the data sheet, specifically page 19 which I will attach below.
    In perusing the data sheet I do not see any way the DRV8837 could back-feed any kind of destructive voltage spikes to the Teensy, so the only conclusion I could draw from the limited information you have provided is what you have admitted to in the first post.
    Click image for larger version. 

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