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DRV8412DDWEVM: Design layout and connections

ArTzy
Genius 16460 points
Part Number: DRV8412DDWEVM

Hi Experts,

Seeking your assistance on this query:

I would like to get, if possible, some more information about DRV8412DDWEVM fabrication of PCB, including its assembly. Also, would be better to know, if connecting M0, M1 and M2 pins to AGND instead of GND can be problematic (I don't think so) as in the datasheet it is connected to AGND, but on your dev board to GND.

Thank you.

Regards,
Archie A.

  • 0
    TI__Guru 55565 points

    Archie,

    AGND connection is preferred like datasheet.  But, GND is also OK as we have produced many of the these EVMs with no issue.  

    The gerber files are available online in the TOOL folder for the EVM.  Is this what you desire?

    Regards,

    Ryan

  • 0 in reply to Ryan Kehr
    TI__Genius 16460 points

    Hi Ryan,

    Thank you very much for your response.

    Follow up questions from Cx:
    About the pcba production, it's certain that all gerber and schematics files are available for public. But What I wanted is the production configuration you applied for your dev board? 

    If I ask otherwise the question, in the case that I would like to produce your dev board which configuration I need to choose here:
    https://be.eurocircuits.com/shop/assembly/configurator.aspx?sessionid=a903b959-5c70-455f-aafb-aa8e699eaecc&lang=en&quantity=2&service=pcbproto&deliveryTerm=3&layers=2&dimY=80&dimX=100
    to get the same pcb as yourth? the thickness of the coil? the overlay used ? is it specific and helps to dissipate the heat? What are the conditions to solder the heatsink of the EVM?
    And an other question, when I go over the 40V of amplitude using your EVM I get some glitches on the down side of the sinus, as like on the photo:
     
    Can you tell me how it appears? 
    PS: I'm using a 60V for PVDD and pwm to generate the sinus. Than after the output of the EVM I have an inductor (the same one that you have on the dev board) and a capacitor (100uF, 100V).
    Thank you.
    Regards,
    Archie A.
  • 0 in reply to ArTzy
    TI__Guru 55565 points

    Archie.

    Is there any indication of FAULT on the nFAULT pins?  Looks like distortion is on decreasing current.  Are you driving a load...what type?  

    For development board, it is 2 layers and 2 oz. copper.  There are thermal calculations in the datasheet.  If you exceed 150C, an external heatsink would be required.

    Regards,

    Ryan

  • 0 in reply to Ryan Kehr
    TI__Genius 16460 points

    Hello Ryan,

    It's to drive a coil load but the signal is distorted without load above 40V. No FAULT or OTW signals are active.

    Further advise. Thank you.

    Regards,
    Archie A.

  • 0 in reply to ArTzy
    TI__Guru 55565 points

    Archie,

    If everything is normal below 40V, possibly some CBC (cycle-by-cycle) current limiting is happening and causing the outputs to disable.  CBC is not reported on the nFAULT pin.  

    Only way to prove this would be to plot the input PWM vs.the output PWM when this is occurring and see if the PWM pulse is being truncated (not matching input).  

    You could decrease the OC_ADJ resistor and that may help the issue as well.

    Regards,

    Ryan