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DRV8301: Drive only 2 lowside

Thierry Quetineau
Prodigy 170 points
Part Number: DRV8301

Tool/software:

Dear Team,

I am doing a special use of the DRV8301. In fact, the design is as a standard BLDC use but I need for a special situation to drive 2 low side (and only these 2 low side) with the third phase at a define voltage.

See the picture below. I would like to drive the low side phase B and phase C with a voltage applied on phaseA.

Not any high side will be driven.

In this configuration, the driver seems in fault mode and not driving the external mosfet but nFault output is not active.

If the BLDC is unconnected, low side are driven but not in case of BLDC connected.

Seems that a fault is detected if voltage is applied on any phase.

  • 0
    TI__Expert 4665 points

    Hello,

    Do you have SPI working? If so, are you able to read the registers to see which fault you are seeing?

    When using the device in special cases like this, you need to make sure no fault conditions are being triggered based on datasheet specs.

    Thank you,

    Joseph

  • 0 in reply to Joseph Ferri
    Prodigy 170 points

    Hi Joseph,

    Working in this situation I don't have the SPI working because the MCU is hold in reset.

    The DRV8301 is shared with auxiliare CPU but unfortunatly without SPI connected.

    I will check deeper how to detect which fault is triggered.

    BR

    Thierry

  • 0 in reply to Thierry Quetineau
    TI__Expert 4665 points

    Hi Thierry,

    Thank you for the update. Let me know if you can determine which fault is occuring.

    This will help us determine the issue and we can create a solution.

    Thanks,

    Joseph

  • +1 in reply to Joseph Ferri
    Prodigy 170 points

    Hi Joseph,

    This morning I try to catch the failure code on SPI. I change a little bit the design for keep main MCU (with SPI) active so.

    Result is that with SPI active no error appears and auxiliar CPU drive properly the low side as expected.

    So, I still not understanding what was the failure but I imagine that the DRV8301 configuration set through SPI should disable or clean some features.

    Now, I will improve the design for discard possible conflict between both low side drive signal (from both MCU/CPU).

    Thanks for your help.

    Thierry