Electronic – Eagle PCB supply symbols in a multi-voltage system

eaglepower supply

Supply symbols signify vdd and gnd and perhaps vdd, gnd and vss in dual supply system.

However, in a situation where one has +5V, -5V, +3.3V, 1.8V, Analogue ground and Digital ground, what should one do about the symbols? There do seem to be 2 ground symbols so ground is not an issue but not many other symbols for nonground supply rails.

Expanding on this question if I am creating a "multi design" PCB with multiple +5V rails, +3.3V rails and grounds where every design has its own area on the PCB with no interaction with other designs, how does one use supply symbols in that case?

Best Answer

In the supply2 library, there are different +5V Symbols you can use those. (If you are a more advanced user you can modify the library and create your own.)

Another way is to use the NAME command and Label each net with XREF, this way it looks quite nice and you can select your own names e.g. +5V/1, +5V/2.

Related Solutions

Electronic – How to facilitate keeping multiple grounds, (i.e. AGND, DGND, etc…) separated in the layout when using Eagle

Create a footprint with GND and AGND pads. Draw copper between these pads. Yes, this will produce a DRC "Overlap" error as shown below:

DRC "Overlap" error in errors dialog

This is OK. There three buttons at the bottom:

Clear all
Processed
Approve

"Clear all" will temporarily clear the list for this run of the DRC. I'm not sure why that's useful; just close the window if you want it shortened.

"Processed" will fade out the color of the red X. This is potentially useful if you're iterating through a long list of DRC errors and fixing them as you go; you can keep track of the ones you think you've corrected.

"Approve" is the only one I use on a regular basis. This moves the error from the errors list to the approved list:

Error moved to approved list in errors dialog

and keeps it there on subsequent runs of the DRC. Note that this only moves this specific error with this specific pair of nets at this specific location. Closing this window and running the DRC again produces the notification "DRC: 1 approved errors"

DRC: 1 approved errors

and no "DRC Errors" dialog. You can get this dialog back by creating an error, or (preferably) the errors command, the yellow exclamation point in the above screenshot, or the menu Tools -> Errors.

The "Approve" functionality exists for a reason, the same reason that we have tools like

#pragma GCC diagnostic ignored "-Warning"

Sometimes, it's OK to ignore a DRC error. This is one of those times.

Electronic – Dual polarity vs dual rail power supply

A typical use of the power supply schematic in the O.P. is for powering one (1) analog circuit, which needs both positive and negative power supply rails. In principle, you can power two (2) completely independent circuits from it (+9 to 0 and 0 to -9). This would be a peculiar scheme, though, because the ground of one circuit is at 9V (plus or minus) w.r.t. ground of the other one. Still, if the circuits are in fact independent, such scheme would work. In practice, this scheme is not used in general purpose desktop power supplies.

A classic desktop power supply (like the one in the YouTube video linked in the O.P.) is of a "dual positive type". Each channel has its own independent secondary winding (or even a separate transformer) and its own rectifier. The channels can float with respect to each-other, and that allows to connect them in series.

Best Answer

Related Solutions

Electronic – How to facilitate keeping multiple grounds, (i.e. AGND, DGND, etc…) separated in the layout when using Eagle

Electronic – Dual polarity vs dual rail power supply

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