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EMC/EMI for TI motor driver IC particular DRV8412

Gordon Su
Intellectual 300 points
Other Parts Discussed in Thread: DRV8412

Hi,

DRV8412 datasheet says the output rise and fall time is typically 14 ns. i measured on the eval board with a motor load. The rise and fall time is pretty close to the specification. my question is that with so fast rise and fall time for motor drive applications will EMC/EMI be a concern? if yes, do you have any experience with any EMI supression component? let's a L-C-L type EMI supression filter is used, do I still need the power ferrite bead for overcurrent protection? as the EMI supression filter will slow down the output current rising rate as well.

Thanks

Best regards

Gordon

  • 0
    TI__Guru 55605 points

    Gordon,

     

    As EMI is very system dependent, it is difficult for me to determine if you will have any problems in your system.  However, I can make some recommendations for counter-measures you can put in place on your board as stuff options.

     

    For conducted EMI compliance, I would recommend a snubber circuit from each output to GND.  3.3ohm and 10nF are the values I would recommend.  For radiated (long motor wire lengths), a LC filter can be used.  Series L on the output with capacitor to GND.  On the DRV8432 EVM, we use 4.7uH and a 0.68uF capacitor to GND.  If you use the series L, the ferrite bead can be removed. 

     

    It is possible that the snubber alone is enough to pass EMI compliance as its function is to slow down the edges.  This, of course, would be the cheapest solution.