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Schematic Sanity Check please... — Parallax Forums

Schematic Sanity Check please...

__red____red__ Posts: 470
edited 2012-02-23 03:09 in General Discussion
This is the most complex schematic and PCB that I have ever designed.

Could people please give it a sanity check? It's designed around the MAX7219.

Advice welcome.

Thanks,



Red

Comments

  • MacTuxLinMacTuxLin Posts: 821
    edited 2012-02-21 18:53
    If it is not a hassle, could you upload a .PDF or image instead? I don't have Diptrace installed.
  • Erik FriesenErik Friesen Posts: 1,071
    edited 2012-02-22 04:36
    Its not the best idea to have ground plane islands, I see you have connected them with traces under the IC's. I would do it a little different. 30 mil tracks are larger than you need for driving leds.
  • tonyp12tonyp12 Posts: 1,951
    edited 2012-02-22 17:40
    Is there a reson that so many traces have to cross path?, is it's becuase the item you connect have it so and can not be changed?

    See how nice I made my triple 595 led board.
    17LED.gif
    17LED.gif
    491 x 111 - 11K
  • __red____red__ Posts: 470
    edited 2012-02-22 18:26
    tonyp12 wrote: »
    Is there a reson that so many traces have to cross path?, is it's becuase the item you connect have it so and can not be changed?

    See how nice I made my triple 595 led board.
    17LED.gif

    That is nice. Wow.

    Unfortunately I do need the connections to be in order so I do have to have crossings. Interestingly Erik above said that I didn't have to use such large traces so I guess I could have passed between the 0.1" pitch headers instead of being silly with vias.
  • __red____red__ Posts: 470
    edited 2012-02-22 20:56
    MacTuxLin wrote: »
    If it is not a hassle, could you upload a .PDF or image instead? I don't have Diptrace installed.

    As requested...schematic.pdf
    pdf
    pdf
    schematic.pdf
    24K
  • __red____red__ Posts: 470
    edited 2012-02-22 20:58
    Erik Friesen wrote: »
    Its not the best idea to have ground plane islands, I see you have connected them with traces under the IC's. I would do it a little different. 30 mil tracks are larger than you need for driving leds.

    So would you normally remove ground plane islands from your circuit or try and connect them via the top layer?
  • MacTuxLinMacTuxLin Posts: 821
    edited 2012-02-22 22:25
    __red__ wrote: »
    As requested...schematic.pdf
    I assume those caps are non-polarized...
    CapSymbol.png
    CapSymbol.png
    403 x 142 - 5K
  • __red____red__ Posts: 470
    edited 2012-02-22 23:43
    MacTuxLin wrote: »
    I assume those caps are non-polarized...
    CapSymbol.png

    Yes.

    My main concern is that this is the first time I've ever designed a schematic from a datasheet. The boards are ordered so they're set in stone (err, copper).

    As a "fail-safe" I printed a "business card" on the back so if they all fail at least they'll have a second lease on life :-)
  • Erik FriesenErik Friesen Posts: 1,071
    edited 2012-02-23 03:09
    It takes some careful routing to remove islands, sometimes you have to run some traces on the top side to allow a decent cross section.

    Note the red circles, for example, those traces could be partially router to the top side to allow the ground plane to connect.
    example.jpg
    1024 x 592 - 157K
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