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DRV8462: Silent Step Function Using Scenario

Brian Wang0
Expert 5310 points
Part Number: DRV8462

Champs,

I noticed we added a silent step mode in DRV8462. In this mode we are using a PI controller to achieve a current close loop. This is well aligned with the trend we see in customer side, where they are try to achieve 'servo-stepper' with closed position and current loop.

Meanwhile we also noted this mode is only for low speed or stand still. May I know why we are not recommending using it for high speed? Is it because of the bandwidth of generic PI controller? Is it a H/W based or S/W based?

Regards,

Brian

  • 0
    TI__Mastermind 45445 points

    Hi Brian,

    Thanks for contacting us via this forum and thank you for this question. The loop controller is hardware based. Stepper drivers tend to be noisy during standstill and slow step rates in lower uSteps settings. Because of this reason we suggest using silent step mode for standstill and low speed. 

    That said, silent step works well at high enough speeds for many applications. The transition frequency to automatically switch from silent step mode can be set to as high as 510 Hz - electrical frequency of the current waveform - see below snippet from the datasheet. The silent step mode continues to work well above this highest threshold. The applicability and tunability will be limited to the stepper motor parameters as well as its operating parameters such as VM and IFS of the application. 

    Please note, in silent step decay mode stall detection will not be operational.

    Regards, Murugavel