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DRV8305: Sense resistor recommendation

Part Number: DRV8305

In the suggested application schematic (for DRV8305), below the low-side MOSFETs there appear to be 3 sense resistors which are in parallel with 3 capacitors going to ground. Are all 3 combinations needed for each phase of the motor? Can we tie all 3 legs together and have an RC combination connecting the 3 legs? 

DRV8305-Q1 EVM, on page 16, has something similar please comment on the suggested values and the above query? 

  • Mohammad,

    The choice of three or one is more of a motor control algorithm problem.

    Individual current sensing (resistor on each leg) is primarily used for FOC control. Single sense resistor is usually used in 6-step or trapezoidal based schemes.

    The datasheet talks about selecting Rsense value based on your design but here is another post I recently made about the same:
    e2e.ti.com/.../740533

    Regards,

    -Adam