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DRV8328: DRV8328

Tekster
Prodigy 120 points
Part Number: DRV8328
Other Parts Discussed in Thread: DRV8305,

Can I disable the overcurrent feature on DRV8328BRUYR?

  • +1
    TI__Mastermind 26046 points

    Yes, connect VDSLVL to GVDD using a 100kohm resistor.

    Thanks,
    Aaron

  • 0 in reply to Aaron Barrera
    Prodigy 120 points

    Thank you Aaron. 

     I am changing over from the DRV8305 to the DRV 8328B.  I want to keep my three phase sensing because of my written software.  What do I need to doon the DRV8328B to be able to keep that?  Right now the DRV8328B combines all three phases and senses one current shunt resistor Rsense.

  • 0 in reply to Tekster
    Prodigy 50 points

    To ask Luke's question a different way:

    If we need to measure each phase current independently through a distinct low side shunt, then we cannot directly tie together the sources of three low side switches at the LSS pin.  Rather, we would add 3 shunts as shown in Luke's marked up drawing, then tie the low side of the shunts together for connection to LSS.  Assuming that we disable the overcurrent sensing in the gate driver and eliminate the Rshunt shown in the drawing, we would then be connecting LSS to ground with a small (0.007Ohm) shunt resistor between LSS and the source pin of each FET.  How will this additional resistance between LSS and the source impact the driving of the low side gate?

  • 0 in reply to ben s
    TI__Genius 15126 points

    Hello Luke,

     

    Thank you for your patience.

     

    You can use the DRV8328 with three shunt resistors and this is shown in the datasheet, however the datasheet has a mistake which is being corrected at the moment. So, please consult the figure below on how to make the connection.

    Please refer to the following E2E if you would like some more information.

    https://e2e.ti.com/support/motor-drivers-group/motor-drivers/f/motor-drivers-forum/1107156/drv8328-question-regarding-the-current-sensing

     

    With this change these are the equations for VDS:

    For high side:

    The VVDSLVL  = IOC * RDS(ON)

    For low side:

    VVDS   = IOC *(RDS(ON) + Rshunt)

     

    Please note that if you implement this system then VSENSE OCP will not work since the LSS will be connected to ground and LSS-GND will not exceed 0.5V.

     

    Best Regards,

    Akshay