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DRV8886: Settling time of IFS in dynamic control by external DAC

Part Number: DRV8886

Hi Team,

My customer is trying to control DRV8886's IFS dynamically by external DAC output. They want to know the settling time(The time from the time the DAC output is quarreled with to the time it is reflected in the IFS) though, Do you have any data of the time?

Regards,

Takashi Onawa

  • Onawa-san,

    I don't have any data. But, we can estimate it according to datasheet parameters:

    a. DRV8886 fstep maximum frequency is 500kHz. Every step the internal current setting could be changed. 

    b.The maximum PWM frequency is 100kHz. Even setting time could be short them PWM frequency, the converter output has to follow the PWM control So, the response time could be longer than few PWM cycle times.

    c.  In most cases, the motor winding inductance limits the winding current changing rate. Let us do the full step operation and read out the current changing rate from one step to next step. That changing rate could be shower than the IFS response time. So, it is limited by the input voltage and winding inductance.