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Package variant with unconnected pins

Former Member

I'm making a symbol for the QFN20 and SSOP24 variants of the SIlicon Laboratories Si473x famiy devices. Apart from the SSOP having more NC and earth pins (which I can connect as duplicates), there's an extra pin (DYBP) on the SSOP which isn't brought out on the QFN. If I add this pin to the device, I get errors using the QFN package because it isn't connected.

 

Is it possible to have a pin in a device which is not available in all package variants? How?

Parents

  • What part of this question is difficult to understand? I'm assuming it must be, because other questions get answered, but not mine.

  • in reply to Former Member

    Thanks, that's what I figured. I had just hoped that there was a different answer image.

    The errors I was getting were a result of not connecting the pad to anything in the

    SSOP, so you get an error when you try to place the SSOP. I hadn't yet added DPYB

    to the symbol, but that would cause the same problem with the QFN.

     

    Eagle's connection tool needs the ability to say "unavailable" for any pin in the symbol.

     

    Would it be possible to place an "infinitely" tiny pin with no keep-out etc, and connect

    to that, or would that create other issues?

Reply
  • in reply to Former Member

    Thanks, that's what I figured. I had just hoped that there was a different answer image.

    The errors I was getting were a result of not connecting the pad to anything in the

    SSOP, so you get an error when you try to place the SSOP. I hadn't yet added DPYB

    to the symbol, but that would cause the same problem with the QFN.

     

    Eagle's connection tool needs the ability to say "unavailable" for any pin in the symbol.

     

    Would it be possible to place an "infinitely" tiny pin with no keep-out etc, and connect

    to that, or would that create other issues?

Children
  • in reply to Former Member

    On 04/10/2013 06:08 PM, Clifford Heath wrote:

    Would it be possible to place an "infinitely" tiny pin with no keep-out

    etc, and connect

    to that, or would that create other issues?

     

    Sure, you could add an extra pad to the package for that purpose.

    Position it somewhere where you're sure there will be no connection.

    When you place the pad, be sure to turn off the stop mask and cream

    layer properties for the pad itself.  If I recall correctly, these are

    check boxes in the properties dialog.  Just copy the QFN.pac to

    something like QFNx and modify the latter.

     

    Enjoy,

        - Chuck