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I've designed a custom PCB for the DRV8874 motor driver. The problem is, as soon as I connect +24V to the board, I hear/see a sparkle on the voltage pin on the header (J1). Huh... but okay, with the motor and +3V connected nothing happens (as it should). Then, I connect +3V to the step pin (pin 1 on the driver/EN/IN1) and the driver burns immediately. White smoke and all. Have no idea what would cause this. I've based the schematic on the Pololu module with this same driver. Tried on few more boards with the same result everywhere - I've also tried to add more capacitance (220uF) but to no avail. Same behaviour on each board which probably means my mistake somewhere. The board has 2 layers.

Schematic

PCB

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  • \$\begingroup\$ No freewheel diodes? \$\endgroup\$
    – Lundin
    Feb 27 at 15:15
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    \$\begingroup\$ Do you have a load connected during your test? Or is the output open? \$\endgroup\$
    – jusaca
    Feb 27 at 15:31
  • \$\begingroup\$ @Lundin Looks like the part has internal diodes for the internal H-Bridge. \$\endgroup\$
    – W5VO
    Feb 27 at 15:31

1 Answer 1

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You swapped the charge pump pin with the motor supply voltage. This could cause your observed behavior, and will prevent proper operation. See your schematic here versus the datasheet reference:

Excerpt from schematic in the original question
Excerpt from Functional Block Diagram in TI DRV8874 datasheet
(Image source: Texas Instruments - DRV8874 datasheet)

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  • \$\begingroup\$ Wow oh wow. Thank you so much! Don't think I would've spotted this any time soon. \$\endgroup\$ Feb 27 at 16:14
  • \$\begingroup\$ @somemisopaste - Hi, Your comment suggests this may be the answer that you needed. As you're new here, please review the page: "What should I do when someone answers my question?". On Stack Exchange, the way to indicate that an answer has solved your problem is to "áccept" it, as explained on that page. That effectively marks the whole topic as solved and indicates which answer solved it. Although áccepting an answer is not mandatory, it's the only way that other people know that you don't need further help, so they don't waste time on already-fixed questions. TY \$\endgroup\$
    – SamGibson
    Feb 27 at 16:40

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