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MCF8329A: Base Current Calculation

Keith Keller
Expert 6600 points
Part Number: MCF8329A

Tool/software:

Hello,

Can you help us understand how to calculate the base current on the MCF8329A?

The data sheet isn't very clear. 

  • current sense resistor 0f 0.5mΩ
  • current sense gain of 20V/V
  • expect an RMS current of ~25A

Thank you, Keith

  • 0
    TI__Genius 13920 points

    Hi Keith,

    When calculating base current we recommend changing either your RSENSE and/or CSA_GAIN so the solution of the equation 1.5 / (RSENSE * CSA_GAIN) to be slightly over the rated max peak current of the motor. in the case of this motor I do not know the max rated peak current, but assuming 60A is close, you would set CSA_GAIN to 5 V/V so that 1.5 / (0.005 * 5) = 60A. 

    When the CSA_GAIN and RSENSE are finalized a scaling factor has to be applied to the value found before so 60 * (32768/1200). Then convert this value into hex and put the hex value into the BASE_CURRENT bit field.

    We have a getting stated video which maybe helpful for setting up the MCF8329A for the first time which can be downloaded using the link below:

    Link: https://tidrive.ext.ti.com/u/jhUObDqVDkKcFQ56/03ca804d-4764-47b7-93ef-dd46c5ac18d7?l

    Access Code: fXJM6S!4

    I will also link here an early version of the MCF8329A Tuning Guide, but this guide is still subject to change: https://tidrive.ext.ti.com/u/0vnfw2Z53-LA-d_V/d499b389-73c3-42ba-91aa-f6156f95139c?l

    Access Code: Z5F1sv/i

    Regards,

    Joshua