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DRV8306: Fuse randomly blowing in BLDC

Part Number: DRV8306

Hi all,

we realized a board with a DRV8306 driving a 24V BLDC motor (see attached diagram) and we are experiencing some issues.

The driver works fine and the motor is driven correctly but sometimes, it happens without no particular bad situation or stress, the fuse F4 blows.
We also tried to replace F4 with a bigger one (time-lag, 7 Ampere) but in that condition we obtained to damage the Q26 mosfet (seems circuit shorted).

Find attached the electrical characteristics of the motor, too.

Can you help me?
Thank you in advance,

2476.BLDC_DRIVER.pdf

  • Hello Marco,

    Thanks for your question and posting to the MD forum. It appears that your motor consumes more than 3A at various scenarios hence why the original fuse was getting blown and not the 7A one.

    Does the DRV8306 trigger a fault at all when the Q26 MOSFET was damaged or when the fuse blows? Have you been able to monitor the switch node as well as the power supply for any fluctuations. If a fault is not getting triggered then this might be hard to catch so it would be useful  to change the VDS setting resistor to decrease the setting. Getting some waveforms will help identify what might be causing the damage.

    Best,

    Isaac

  • Hello Marco,

    Did you still need any help on this thread or is it okay to close?

    Best,

    Isaac

  • Hello Isaac,

    we are performing some more test and I'm trying to investigate deeper.

    However, you were probably right about the motor consumption (and the 7A fuse was too high).

    If this doesn't bother you, I would like to keep this thread open and then get back to you in the next two or three weeks.

    Thanks,

    Marco

  • Hello Marco,

    Of course I can leave this thread open, if you run into any problems feel free to post on the thread. They do auto-lock after some time, in case if that happens to you feel free to start a new one and we would be glad to help you. All you need to do is select the "ask a related question" or "ask a new question" on the top right.

    Best,

    Isaac