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I am utilizing the A3967 Allegro microstepping driver with translator. The problem is that I'm burning out the driver when the stepper motor is seemingly disconnected. This doesn't happen every time I disconnect the stepper motor, but after disconnecting enough times I believe every board is susceptible to this failure mode. The Load Supply for my circuit is +12VDC and the current to the stepper motor is 0.5A (limited with the sense resistors). The circuit also has a 25V 100uF Tantalum smoothing capacitor at VBB1. The kicker is, I believe the stepper driver is only burning out (shorting) when this capacitor is populated on the PCB. I can't seem to get the stepper driver to burn out when I remove this capacitor, no matter how many times I disconnect the stepper motor. What could explain this? I posted the block diagram from the A3967 datasheet below (A3967 datasheet).

Allegro Website: https://www.allegromicro.com/en/products/motor-drivers/brush-dc-motor-drivers/a3967

I can't add the schematic or a picture of the board.

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Thank you for your help in advance!

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It sounds like you are disconnecting the step motor while the driver has it powered. Under no circumstances should you do that. The step motor windings are inductive and there will be a huge spike in voltage when you disconnect. It could be in excess of 1000 volts! Under these circumstances, the driver may cease to operate.

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