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DRV8412: What is the closest motor drive spice model?

craig Garvin
Prodigy 20 points
Part Number: DRV8412
Other Parts Discussed in Thread: DRV8876

Hello -

We are using the DRV8412 in our EndoVascular Robot and seeing some overshoot in the PWM output voltage that we are trying to understand and control. I've been trying to develop a spice model of our drive circuit and was not able to find it (DRV8412) in the TI-Spice library. I've tried using DRV8876 but it has additional configurations that are complicating the task. Before I try to debug the DRV8876, I figured I would check with support & see what the recommendation is. 

Thanks  

  • 0
    TI__Mastermind 21690 points

    Hey Craig,

    That's a good question, let me check with a coworker on it.

    In the meantime, do you want to post some scope captures of the output voltage overshoot and maybe your PCB schematic?  We can help debug the overshoot issues.  Could be insufficient bulk capacitance, or PCB layout improvments - Best Practices for Board Layout of Motor Drivers

    Regards,

    Jacob

  • 0 in reply to Jacob Thompson
    Prodigy 20 points


    TI DRV8412 drive schematic.pdf

    OK, I've attached the drive schematic. The motor is driven accross M1_MOB to M1_MOA and has about 20 ohm resistance & 575 uH inductance. The 'current probe' is a standard tektronix and 'iSense' is the output of a differential op-amp across R108.

    Certainly would welcome any insight. Thanks 

  • 0 in reply to craig Garvin
    TI__Mastermind 21690 points

    Hey Craig,

    Thanks for the pic.  I see you already have a RC snubber circuit on there, that was the first thing I was going to suggest.  We could try tweaking those values, but let's leave it as-is for now. 

    I see your VMOT circuit only has 10uF bulk capacitance - I suggest trying a much larger value here.  For testing purposes I would try 47uF or 100uF and see if that improves things.  GVDD could also use more capacitance, like 100uF.  

    Is this a new design?  If so I have some much newer devices that I think would work better for you if you can give me the peak and RMS/continuous current and operating voltage.  

    Best,

    Jacob

  • 0 in reply to Jacob Thompson
    Prodigy 20 points

    Jacob -

    Thanks for the great tips! We will definitely test these out. To answer your question, we've made it through a fair bit of validation with this design, so we would prefer to stick with it. 

    Back to my original inquiry: Are there any SPICE models that you would recommend as a starting point  to model this part? 

    Thanks 

  • +1 in reply to craig Garvin
    TI__Mastermind 21690 points

    Hey Craig,

    craig Garvin said:
    Are there any SPICE models that you would recommend as a starting point  to model this part?

    Unfortunately there isn't anything great.  DRV8412 is unique with a bootstrap architecture vs the charge pump found in most of our drivers.  It also has unique dead time and switching speed capability for our drivers.  Your route of using DRV8876 is as good as any, but basically at that point you're just modeling "any" BDC driver.  

    Regards,

    Jacob