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PowerPad for DRV8801

Neil Landers
Prodigy 40 points
Other Parts Discussed in Thread: DRV8801
This is my first post and I'm jumping right in.

I'm creating the footprint for the DRV8801PWP in Orcad PCB Editor and could use some help. Hopefully some of the gurus on here use Orcad and PCB Editor!
 
Right now I'm creating the pad for the powerpad and am a little confused.  The specs for the powerpad are on page 23 of the spec sheet: http://www.ti.com/lit/ds/symlink/drv8801.pdf

I'm using Pad Designer to create the pad for a 2 layer board. I'd like the thermal pad to be part of the ground plane. Here is a list of my padstack layers:
Begin Layer Rect 5.00x3.4 (in mm)
Default Internal: Null
End Layer: Rect 5.0x3.4
SolderMask_Top: Square 3.00
SolderMask_Bottom: Null (I don't want a any of the pad on the bottom exposed)
PasteMask_Top: I haven't figured out what this should be yet

Do I have this right?

I also have specified multiple drill in a 2 rows by 2 columns pattern to get the thermal vias. The Drill diameter is 0.33mm per the spec. 
 
Please let me know if I am doing anything incorrect!  
Thanks in advance! 
  • TI__Guru** 114905 points

    Hi Neil,

    We use Altium here so are not completely familiar with Orcad.

    TI provides schematic symbols and footprints using a generic program call Ultra Librarian.

    The DRV8801 PWP package is available under the Quality and Packaging tab of the DRV8801 product folder. See http://www.ti.com/product/DRV8801/quality then scroll down to CAD/CAE symbols.

    This will give you a reference if you want to build your own.

  • Prodigy 40 points

    Rick,

    Thanks for your help.

    I was able to use the Ultra Librarian viewer to export a DRV8801PWP to in Allegro 16.0 format.. (Had to get the files from Ultra librarian installed on a win 7 pc and move em to my win xp pc running Orcad because the Ultra Librarian installed on the XP machine couldn't find the parts for some reason)

    Interestingly, the full functionality of the powerpad doesn't seem to have been utilized. It was designed to be single layer only hence no thermal vias or additional powerpad layers.

    I am not sure if the extra heat sinking will be needed, but for now, i'll leave it as is. .

  • in reply to Neil Landers
    TI__Guru** 114905 points

    Hi Neil,

    Thanks for pointing this out. We will check into the lack of thermal vias.

    When we create an EVM, we typically connect the thermal pad through thermal vias to the opposite side of the PCB. This is critical in the RTY package.

  • in reply to Rick Duncan
    TI__Genius 14455 points

    Hi Neil,

         The current footprint for the PWP package of DRV8801 does not have thermal vias. We will get you a footprint in UL with thermal vias shortly.

    Regards,

    Gerold

  • in reply to Rick Duncan
    Prodigy 40 points

    I thought it was pretty important.  The spec certainly emphasizes it. I actually added a couple 0.33 mm diameter holes to my footprint. They are plated holes, so they should conduct with the other size of the board, assuming the other side of the board is a ground plane. Unfortunately, this is giving me all sorts of DRC errors.  I think it's related to the drill file, but I'm not sure.  Either way, a proper footprint would be greatly appreciated!  

    Thanks again. 

  • in reply to Neil Landers
    TI__Mastermind 20985 points

    Hi Neil, of course, you'll want to have vias under the power pad, which have an annular ring of exposed metal.  You mentioned drill holes and I'm not sure if that's the same thing.  Hopefully Gerold can get you a footprint soon.

    Best regards,
    RE

  • in reply to RE
    TI__Genius 14455 points

    Hi Neil,

         Please see the BXL file attached with thermal vias. This will be uploaded to ti.com shortly.

    Regards,

    Gerold

    2112.DRV8801_PWP_16.bxl

  • in reply to Gerold Dhanabalan - Online Design Tools
    Prodigy 40 points
    Gerold, 
    It compiled, but not without me jumping through hoops.  I had to create the symbol in orcad on my other work PC because some file didn't exist.  
    Anyways, when I save the symbol after opening it, I get a DRC error that says there's a duplicate of pin 17.  Any idea what that is about? 
    Thanks for the new footprint!  
    Neil
  • in reply to Neil Landers
    TI__Genius 14455 points

    Hi Neil,

        It is the vias on the footprint. You should be able to export the symbol to Orcad capture using the UL reader.

    Regards,

    Gerold