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!


  • Electronics Layouts v4.pdf
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Not that i am a pro in electronics, but shoudnt the batteries GND be somehow connected to the Teensys GND?
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


  • Electronics Layouts v5.pdf
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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.
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