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BoostXL to drive different MOSFETs

Alan Lindner
Intellectual 500 points
Other Parts Discussed in Thread: DRV8301

I took the BoostXL board and spun the kit motor from the DRV8301-LS31.  I then removed the MOSFETs and replaced with wires to my inverter using the same Vishay MOSFETs as the DRV8301-LS1.  Motor spun.

Finally, I connected the modified BoostXL board to my custom inverter using IR MOSFETs that require gate driver current of 0.656A (=105nC/160ns).  Motor does not spin and I get a fail. 

Is the default max gate current from the DRV8301 set at the max setting?  Is that peak or average?

I used wires from the board to the inverter but placed a large cap at the inverter.  Will the wire length effect the circuit?

Thanks Alan

  • 0
    TI__Mastermind 21305 points

    The default setting is for 1.7A. This is peak current.

    The wires are from the DRV8301 to the MOSFETs? Inductance in the gate signals may cause issues. What FAULT is the DRV8301 reporting?

    Where is the cap located? On the gates or across the half-bridge? Capacitance on the gate will increase the charge required from the gate driver.

  • 0 in reply to Nicholas Oborny
    Intellectual 500 points
    I removed the MOSFETs and soldered wires to the pads on the PCB.
    Cap is located at the new inverter next to the MOSFETs. Across the half bridge.
  • 0 in reply to Alan Lindner
    TI__Mastermind 21305 points

    Can you take some scope plots of the signals of each side of the wires?

    It would also be good to understand which FAULT is coming from the DRV8301.

    Are the MOSFET's and DRV8301 sharing a power supply? The overcurrent protection for the high side MOSFET is sensed between PVDD1 and SH_X. If PVDD1 differs from the MOSFET supply it could be throwing a false overcurrent.

  • 0 in reply to Nicholas Oborny
    Intellectual 500 points
    Will do. I connected up another BoostXL that has NOT been modified and ran the motor for a while. All was working. We have a GUI that shows all the BackEMP voltage, shunt current and Faults. As I changed the PWM percentage to make the motor go faster, all was working at 60% PWM and then ....FAULT. Fault light on board but not thru SPI. OTCW light did not come on.