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DRV8434S: and DRV8452S　Timing when current and excitation settings can be changed

Taito Takemura
Expert 3260 points
Part Number: DRV8434S
Other Parts Discussed in Thread: DRV8462

Tool/software:

Hello team,

Could you please tell me if it is possible to change the current and excitation settings during excitation (motor stopped/rotating) of DRV8434S and DRV8452S?

Could you please tell me the timing when it is possible to change the current and excitation settings, and when the settings are reflected in the IC and it operates with the changed settings?

Thank you for your help.

Regards,

Taito Takemura

  • 0
    TI__Intellectual 2550 points

    Hi Takemura-san, 

    Please give us a day to look into this and get back to you. Thanks.

    Regards,
    Karan

  • 0 in reply to Karan Doshi
    TI__Mastermind 45445 points

    Hi Takemura-san, 

    How does the current setting change? Is it by VREF voltage or TRQ_DAC register setting?  What did you mean by excitation setting? was it uStep modes? 

    Regards, Murugavel

  • 0 in reply to Murugavel4637
    TI__Expert 3260 points

    Hi Murugavel,

    > How does the current setting change?

    In order to achieve energy savings and provide appropriate torque depending on the operation timing, they need to change the output current settings while the motor is stopped/rotating, and change the excitation settings while the motor is stopped.

    The parameters are changed via SPI communication.

    >  Is it by VREF voltage or TRQ_DAC register setting? 

     Is it by TRQ_DAC register setting

    > What did you mean by excitation setting? was it uStep modes? 

    It is difficult to generalize because there are various cases depending on the place of use, but for example, they change from 1A to 0.5A or from 0.5A to 1A while the motor is rotating.

    Thank you for your help.

    Regards,

    Taito Takemura

  • 0 in reply to Taito Takemura
    TI__Intellectual 2550 points

    Hi Takemura-san, 

    Will get back to you on this in a day.

    Regards,
    Karan

  • 0 in reply to Karan Doshi
    TI__Mastermind 45445 points

    Hi Takemura-san, 

    All SPI register writes will take effect immediately after the nSCS pin goes logic HIGH after the SPI frame. So TRQ_DAC update will go in effect immediately after nSCS = HIGH. 

    You mentioned "In order to achieve energy savings and provide appropriate torque depending on the operation timing, they need to change the output current settings while the motor is stopped/rotating, and change the excitation settings while the motor is stopped.". This is a built-in new feature in the DRV8452S, DRV8462 family of devices known as Auto-torque. Customer can enable and setup this mode to achieve the same function automatically. Please refer to this application note, https://www.ti.com/lit/an/slvaff1/slvaff1.pdf. Thanks.

    Regards, Murugavel