Track size for GND ( analog vs Digitial)

[akhodeir]

Hi All,

I build a system which has low current components (microcontroller, digital components) and high current components ( mosfets, motor dirvers ,…etc).

I assigned the GND of the battery to a class which has 1 mm track size. I found all low current and high current connections to GND has 1 mm track size. Of course this is expected.

I aim to have GND of the high current components to have wide track size and the low current components to have narrow track sizes. any solutions ?

It is possible to do this manually but I use freerouting blugins to automate the routing for me.

[bask185]

Usually one does not use traces for GND but one uses copper zones to connect grounds.

You can use top, bottom or both layers for ground. I usually use both.

If you do have some reason to use traces, I would not assign a specific width to the GND traces. But manually select a decent trace width once you are routing.

I made these settings for myself. It accomodates all projects of mine so far.

Hope it helps.

Regards ,

Bas

[akhodeir]

Many thanks for the answers.

I didn’t use a layer as a GND before. I will sure give it a try.

actually, I don’t have any reasons for using GND traces. I am just a beginner and this is how I started.

it seems you use different track net classes to assgin the width of a track and I state this as a manual routing which I don’t use.

I use freerouting blugins which do everything automatic to save me time. I was thinking there are tricks to define a GND for analog components to make them large and others to make narrow.

[Tojan]

if you want to use different GNDs for analag, digital etc. the usual practice then is to do exactly that but already in the schematic. in the default power lib you will find different grounds like GNDA, GNDC etc. You then connect the GND of analog components for example to the GNDA symbol instead of the general GND and now you will also have the two different GNDs in the layout. to connect them somewhere in the layout you should then use a net-tie.

However in general GND separation is a delicate manner which can result in all kinds of problems. for your case I would recommend just routing these lines by hand with the sizes you want them to be. autorouters are helpful but cases like these are the reasons why layout designers still have plenty of work to do today.

[jmk]

@akhodeir

I use freerouting blugins which do everything automatic to save me time. I was thinking there are tricks to define a GND for analog components to make them large and others to make narrow.

Hi @akhodeir
Although Freerouting may work on Kicad, it is not part of the Kicad EDA. It is best if you ask this question on the Freerouting forum.