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DRV8316: current limit

Part Number: DRV8316

I have a couple of questions regarding the current limit when in mode 2 mode (6x pwm with current limit).

Does the current limit work when in brake mode since IA + IB + IC = 0?

If not what does the note on page 42 mean? 

Thanks

  • Hi DTruex, 

    We will investigate this further with the team to assess device current-limit feature behavior during braking.

    As an initial response, here's my understanding of the note: 

    1. when a motor driver system undergoes 'BRAKING' procedure, the low-side MOSFETs for all 3-phases are turned on to discharge the phase winding voltage and current to GND through the LS active MOSFET channels. This operation is depicted in Figure 8-37 above. 
    2. However, depending on the overall system behavior, this operation may trigger faults on the protection features such as the OCP (Overcurrent Protection) or CBC ILIM (Cycle-by-cycle Current Limit).
    3. when this happens, the LS MOSFETs will be turned OFF since the DRV system is in shutdown-mode, and the system will undergo diode-freewheeling/demagnetization state in which the phase current is recirculated to the VM DC_BUS through the HS MOSFET body diodes

    Based on this info, I would say that the note is just highlighting what will happen if a system fault is triggered, and that fault could be from the current limit protection feature (which I assume is working during braking operation). 

    Best Regards, 
    Andrew 

  • Hey DTruex,

    I just wanted to provide some additional information to what Andrew provided.

    When you are in the brake mode there is no current flowing so the protection will not be triggered.
    In the note, the over current protection is specifically referring to the cycle by cycle current protection, which will not trigger when the motor is stationary. When the motor is spinning and brake mode is asserted, the motor can trigger the cycle by cycle current limit if there is a large amount of load current or Back-EMF from the motor when the motor is stopping.

    The following E2E might provide some more relevant information.

    DRV8316: about current limit - Motor drivers forum - Motor drivers - TI E2E support forums

    I hope this offers some clarification. Please feel free to reach out with any questions you might have.

    Best Regards,
    Akshay

  • Hey DTruex,

    Just reaching out to ensure that your questions have been answered. Feel free to reach out if you have anymore questions.

    If your question has been answered please mark the thread as resolved. 

    Best Regards,

    Akshay

  • Hey DTruex,

    I am closing the thread, but feel free to reach out if you have any more questions.

    Best Regards,

    Akshay