How do I combine 2 Power Layers on one physical layer (e.g. AVDD/DVDD)

On 2/1/2012 11:55 AM, Dave Comer wrote:

Does any one know of a way, or have a strategy, to combine two power rails on one layer. That is, say for example I want both analog and digital Vdd (say AVdd and DVdd) to exist on a single layer of a 4-layer PCB. The combined layer would have AVdd and DVdd tied together at only one physical point (at a main device GND pin) where the ground and sense lines connect to the layer. For sake of discussion, say layer 1/4 are signal layers, layer 2 is Vss, and layer 3 would be the combined AVdd/DVdd layer. I guess you could think of this as AVdd existing on the top of the layer, and the DVdd drawn on the lower half of the layer with the tie point in the middle.

 

One way to do this would be two separate layer and combine them when I generate the Gerbers. However, I'm not sure how this can be done logically in Eagle allowing Eagle to generate the relieves for the power pins without some type of (yet to be determine layer eqation in the design rule specification.

 

Does this make sense?

 

Thanks,

Dave

 

I usually draw 2 polygons on the same layer.  Name one DVdd and one AVdd.

Jim

Jim,

Hum, I didn't think of that (less experience user issue) but I see in the manual pps. 150-153 ("Defining a Copper Plane with a POLYGON" and page 160 ("Supply Layers with Polygons and More than One Signal"). Thanks for the suggestin Jim. That's got me headed in the right direction.

Dave

On 2/1/2012 7:34 PM, Dave Comer wrote:

Jim,

 

Hum, I didn't think of that (less experience user issue) but I see in the manual pps. 150-153 ("Defining a Copper Plane with a POLYGON" and page 160 ("Supply Layers with Polygons and More than One Signal"). Thanks for the suggestin Jim. That's got me headed in the right direction.

 

Dave

 

Glad to help.   I am a newer user too!  In general the recommendation I

encounter frequently is to use polygons in preference to supply layers.

   Polygons are much more flexible.

Cheers,

Jim

Am 02.02.2012 02:05, schrieb Jim Littlefield:

On 2/1/2012 7:34 PM, Dave Comer wrote:

>> Jim,

>>

>> Hum, I didn't think of that (less experience user issue) but I see in

>> the manual pps. 150-153 ("Defining a Copper Plane with a POLYGON" and

>> page 160 ("Supply Layers with Polygons and More than One Signal").

>> Thanks for the suggestin Jim. That's got me headed in the right

>> direction.

>>

>> Dave

>>

>

Glad to help. I am a newer user too! In general the recommendation I

encounter frequently is to use polygons in preference to supply layers.

Polygons are much more flexible.

 

Cheers,

Jim

 

IMHO support layers are not used anymore in ver.6.

--

Mit freundlichen Grüßen / With best regards

Joern Paschedag

>>

>

IMHO support layers are not used anymore in ver.6.

 

That is correct.

Supply layers were deprecated for V6.

hth,

Jorge Garcia

Cadsoft Support

I just had a good conversation with Ed at Eagle about this topic (I finally got back to finishing the board I am working on). What I was missing is that I needed to deselect the power supply option on the inner layers (in my case 2 and 3 or Vss/Vdd respectivley) to make the polygons "smart"; smart in the sense the thermal reliefs are added to the layer for the polygon. I also didn't realize (I thought I had read the fine manual but clearly missed this) that the $ make the layer a negative layer. So, with the layer not lacking the supply option ($ sign), using the command "POLY <signal name>" (say this tip on instructables.com - could have also added the polygon and named it later), I now have solid polygon copper areas where I want them as Vdd/AVdd, Vss/AVss. That said, I hope to upgrade at work to to version 6 soon (I have upgrade for my personal copy), as Jeorge and Joren pointed out supply layers are depricated in version 6.