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Connected signals to inner layers

autodeskguest

Question on being sure signals are connected as expected..

 

The inner 2 layers of a new 4 layer board are power.

One is the common return.  The layer name (SYS_GND) is the same as the

routed trace signals names, so no connection concerns there.

 

The other will provide individual supply voltages (5V and 3.3V).  At

this point, that layer is named Fused_5V, and the traces to connect

either "Fused_5V" or "+3.3V_SYS".  How can I be sure the +3.3V_SYS vias

will correctly connect to the dual supply layer??

In a similar manner, there are several isolated supply and return areas

physically located in those layers, connecting to top and bottom traces

as needed.

 

Question is asked since a mistake was unknowingly made on another 4

layer board, where there were different names between layer and signal,

  resulting in all "5V_supply" vias not connected to the supply plane.

 

Thanks

 

 

  • Ken wrote on Thu, 17 December 2009 16:09

    The inner 2 layers of a new 4 layer board are power.

    One is the common return.  The layer name (SYS_GND) is the same as the

     

    routed trace signals names, so no connection concerns there.

     

    Are you sure?  I thought a layer that is to work as a plane needs to have

    the name of the net with a $ in front of it, like $SYS_GND.

     

    Quote:

    The other will provide individual supply voltages (5V and 3.3V).  At

    this point, that layer is named Fused_5V,

     

    Since you want multiple nets on that layer, its name doesn't matter.  Just

    leave it at "2" or "3".  What matters is that the names of the polygons

    match the names of the nets you want them to be part of.

     

    Quote:

    How can I be sure the +3.3V_SYS vias

    will correctly connect to the dual supply layer??

     

    You don't connect to a "layer" unless that layer is a complete plane.  You

    will have to create polygons in this layer for the various supply signals

    you want there.  You will have to decide where the 3.3V power rail will be

    and the 5V power rail.  Once you have decided which regions will be which,

    you draw polygons over those regions that have the names of the nets you

    want them to connect to.

    --

    Browser access to CadSoft Support Forums at http://www.eaglecentral.ca

     

  • confused by your question

     

    if you have more than one "plane" on a layer, it should be made with

    polygons not planes. in general, use polygons not planes. each poly can

    have it's own name and belong to a net. they will automatically avoid

    other signals laid out on the layer.

     

    if you intend fused_5v and +3.3v_sys to be the same node, then you

    should name them the same.