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BOOSTXL-DRV8323RS: ALIGN mode in 1X PWM. How to enter

Bill Brown77
Prodigy 20 points
Part Number: BOOSTXL-DRV8323RS
Other Parts Discussed in Thread: DRV8323

I am spinning a BLDC motor using the DRV8323SR.  Works well.  The motor we are using doesn't have a position sensor, so we added our own.  We need to calibrate the position sensor for each motor since the position magnet could be installed at any angle.  To do this we need to position the motor at 0 degrees and run a calibration program.  One way to position the motor is to pulse one leg of the motor with PWM and sink the other 2 phases.  That will move the motor into position we need prior to calibration.

The DRV8323 data sheet shows a table (table 5) that has a row called "Align".  This is exactly what I need.  However there is no other mention in the data sheet of how to enter this state.

Can anyone tell me how to do this?

Thanks.

Bill

  • 0
    Prodigy 20 points
    I may have my own answer. I think I need to assert INLA, INHB and INLB to enter this state. This will be difficult since these are the 3 hall-effect signals and are driven by the position sensor. All ones is not a legitimate position which is probably why TI used this combination.
  • 0
    TI__Guru** 114905 points
    Hi Bill,

    To enter the align state, set INLA = INHB = INLB = 1 at the inputs of the DRV8323RS.

    The align state can be used in either Synchronous 1x PWM (Table 4) or Asynchronous 1x PWM (Table 5) modes.
  • 0 in reply to Rick Duncan
    TI__Guru** 114905 points
    Hi Bill,

    You are correct. It may be difficult but can be done if:

    the mcu is reading the hall-effect signals and providing the 1x PWM inputs OR
    external circuitry is placed in series with the three hall-effect signals from the 1x PWM inputs, allowing the hall-effect signals to be disabled and the pullups to set the 1x PWM inputs high.

    If you are considering the latter, the TI FemtoFETS like the CCSD13381F4 are good choices due to size and performance.