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BOOSTXL-DRV8305EVM: DRV8305N

Adam
Expert 1225 points
Part Number: BOOSTXL-DRV8305EVM

At BOOSTXL-DRV8305EVM the REF pin is connected to 3.3V, this gives offset of 1.65V (when k=2) to the Current Senses.

But for low-side current sensing we never have negative current, right?

Current always goes with this direction (red arrows below), right?

So do we need to bias the CS Amplifiers when using low-side sensing? Is there any reason for that?

VREF shouldn't be tied simply to GND? (for DRV8305N)

thanks,

Adam

  • 0
    TI__Genius 15745 points

    Hi Adam,

    Thank you for your E2E post!

    Let me look into this for you and discuss with some teammates of mine, I'll give you an update by the end of the week.

    Regards,

    Yara

  • 0 in reply to Yara Al Shami
    TI__Genius 15745 points

    Hi Adam,

    Adam said:
    But for low-side current sensing we never have negative current, right?

    There are many instances where negative currents are present. This typically occurs during the commutation phase when the current direction through the low-side shunt resistor changes as the motor's magnetic field rotates. Negative current readings in low-side current sensing for BLDC motors are a normal part of the motor control process and are used by the control algorithm to ensure effective and precise motor operation.

    Adam said:
    So do we need to bias the CS Amplifiers when using low-side sensing? Is there any reason for that?

    When using low-side current sensing, where the current flows through the low-side shunt resistor, you typically don't need to bias the CS amplifiers.

    Adam said:
    VREF shouldn't be tied simply to GND?

    Based off the EVM schematic it looks like VREF is connected to 3.3V

    Regards,

    Yara