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INA214-Q1: bandwidth

Colt Zhang
Expert 3500 points
Part Number: INA214-Q1
Other Parts Discussed in Thread: INA240

hi team,

now my customer want to use  INA214-Q1 to sense the current of motor, The motor speed is based on 100rpm, current sampler scheme, phase current frequency is approximately 14Hz, PWM frequency 20KHz,ADC sampling frequency 20KHz, what bandwidth does the current sampler need to meet?

how to calculate the  bandwidth?

  • 0
    Guru 140200 points

    Hi Colt,

    from your description the bandwidth needs to be 20kHz plus the harmonics plus a certain reserve. I think a bandwidth of 200kHz should be adequate.

    Kai

  • +1 in reply to kai klaas69
    TI__Expert 4720 points

    Hello,

    Are you trying to get the average current during that PWM cycle or do you need to be more accurate? Will the ADC sample in the middle of the PWM cycle?

    I would agree with Kai 30kHz is will not be sufficient.

    You may have some issues with common mode switching from the PWM (if you are measuring inline with the motor). We have a specific part that tackles this problem please see the INA240/241. These parts have a PWM rejection feature that is for motor drive applications like the one mentioned above. 

    Regards,

    Cas