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DRV8313: Drv8313 is not stable in use

Bangjing Zhu
Prodigy 70 points
Part Number: DRV8313

Hi, Ti engineer

Recently, I took over an actuator project and found a strange phenomenon. Drv8313 is connected to BLDC and does not supply power to drv8313. Dragging BLDC finds that sometimes there is braking phenomenon, sometimes there is no braking phenomenon (power supply circuit and PGND circuit have been disconnected). Why is this?. In order to eliminate the influence of my peripheral circuit, I broke all the pins of drv8313 (except the three pins connected to the motor), and found that there were still braking phenomena sometimes and sometimes none. Three of them were tested, and there was no rule~

seek help

seek help

seek help

  • 0
    TI__Guru 65190 points

    Bangjing,

    If I understand your question correctly, all pins of the DRV8313 are disconnected from the PCB and only OUT1/OUT2/OUT3 are connected to the motor?

    Can you show a picture?

    Regards,

    -Adam

  • 0 in reply to Adam Sidelsky
    Prodigy 70 points

  • 0 in reply to Bangjing Zhu
    TI__Guru 65190 points

    Bangjing,

    Can you show us a scope image of the motor terminals during these two conditions?

    Regards,

    -Adam

  • 0 in reply to Adam Sidelsky
    Prodigy 70 points

    first is connection diagram

    second is brake phenomenon waveform

    third is no brake phenomenon waveform

    fourth is no brake phenomenon but limit speed waveform

  • 0 in reply to Bangjing Zhu
    Prodigy 70 points

    I just got the development board(DRV8313EVM) and found that the phenomenon is consistent.

  • 0 in reply to Bangjing Zhu
    Prodigy 70 points

    The drv8313 needs to be powered on and activated to avoid braking. However, if the drv8313 is not operated for a long time after activation, there will still be braking phenomenon.

    Is this a bug?

  • 0 in reply to Bangjing Zhu
    TI__Guru 65190 points

    Bangjing,

    Do you see any FAULT reported on the nFAULT pin when the device is activated and the braking phenomenon is occurring?

    Regards,

    -Adam

  • 0 in reply to Adam Sidelsky
    Prodigy 70 points

    Hi，Adam

    Because the voltage is too low to judge whether there is a fault.

  • 0 in reply to Bangjing Zhu
    TI__Guru 65190 points

    Bangjing,

    I don't understand why nFAULT cannot be measured.

    Regards,

    -Adam

  • 0 in reply to Adam Sidelsky
    Prodigy 70 points

    Hi,Adam

    Because the voltage is too low to judge whether there is a fault. 

    I cant get any signals.

    Could you do some related tests?

  • 0 in reply to Bangjing Zhu
    TI__Guru 65190 points

    Bangjing,

    We have provided complete details on this case and the root cause to your FAE, Eric Xiong.

    Please follow up with Eric.

    Regards,

    -Adam