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DRV8323: About the specifications

Liu Yang
Expert 8715 points
Part Number: DRV8323

Hi Team,

I would like to know about Figure 27 (TDRIVE State Machine) in specification DRV8323.

The input signal is not simultaneous due to the dead time of the CPU.

I think that the time difference between VINHx and VINLx is not a problem if the register setting is appropriate, but is it correct?

Also, please let us know if you have any concerns or precautions due to the time difference.

Best Regards,

Tom Liu

  • 0
    TI__Mastermind 23356 points

    Hey Tom,

    Thank you for your question.

    I have assigned a team member to provide feedback. Please note that there might be some delay due to Thanksgiving Holidays.

    Best,
    Akshay

  • +1
    TI__Mastermind 26466 points

    Hi Tom,

    Thanks for your question! You are correct that having MCU deadtime will not be an issue. I have included a more up to date TDRIVE diagram shown below. If there is MCU deadtime inserted, this will result in the tdrive timer restarting once the input toggles. The tdrive timer resets every time an input is toggled. This will result in the IDRIVE being applied a little longer (before switching to IHOLD), since the IDRIVE current is applied until the end of tdrive. Let me know if you have any additional questions!

    Regards,

    Anthony Lodi

  • 0 in reply to Anthony Lodi
    TI__Expert 8715 points

    Hi Akshay,

    Thank you for your answer.

    The input waveform VINHx collapses from around 1.3μs, and the output waveform also collapses.

    If the DRV8323 is not running, the input waveform can be seen correctly.

    It seems that there is a limit to the duty during operation, and we are verifying the ON time of VINHx to avoid this current situation.

    Please let me know if you have any information about the minimum ON time of VINHx during operation.

     

    Best Regards,

    Tom Liu

  • 0 in reply to Liu Yang
    TI__Mastermind 26466 points

    Hi Tom,

    Sorry for the delayed response! The team was on holiday vacation in the U.S. Thursday and Friday. 

    If the input waveform is collapsing when the duration of the input is less than 1.3us, that seems to be a limitation of the microcontroller and not the driver. Could you provide a waveform showing the input waveform collapsing? 

    Regards,

    Anthony Lodi

  • 0 in reply to Anthony Lodi
    TI__Expert 8715 points

    Hi Anthony,

    Thanks for the information.

    I found a problem with the dead time setting on the MCU side.

    We plan to check if the input and output waveforms return to normal after resolution.

    We will inform you of the results later.

    Best Regards,

    Tom Liu

  • 0 in reply to Liu Yang
    TI__Mastermind 26466 points

    Hi Tom,

    Glad to hear that it seems you may have found the solution to the problem! Looking forward to the results.

    Regards,

    Anthony Lodi