Author Topic: Power from trace vs copper pour  (Read 321 times)

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Offline newtekuserTopic starter

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Power from trace vs copper pour
« on: February 03, 2024, 08:00:50 pm »
Let's say in my schematic I have a capacitor connected to a power pin, the simplest way I know how to route the connection between the two is by connecting a trace between the positive terminal of the cap to the positive terminal of the power pin, and negative terminals using vias to the ground plane.
Lately I've gotten "fancier" using copper pours connected to the power net, so now I'm simply dropping the fooptrint of the capacitor onto the copper pour and connect the ground pin to the ground plane using a via. I no longer have to connect the positive terminal of any components placed on this copper pour because they are all connected to power.

If now I place components on copper pours like in the example above, I can place them wherever I desire as long as they are on the copper pour and connect to the correct net. As a newbie, this raises some questions:
1. If I have components that need to connect with others in parallel or series, how does placing them on a copper pours without traces affect their connections? (I think my problem is that I'm visualizing them as they are connected in the schematic)
2. Also, what happens if I place this capacitor farther away from the power pin? (let's say the cap now sits physically behind another component)

I do have designs using copper pours that just work but I'm questioning how it is possible.

Hope my question makes sense.
 

Offline JustMeHere

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Re: Power from trace vs copper pour
« Reply #1 on: February 03, 2024, 08:54:01 pm »
If your pour isn't solid and is full of slots, you will have noise problems.
 

Offline Clear as mud

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Re: Power from trace vs copper pour
« Reply #2 on: February 04, 2024, 05:07:52 am »
Components are still in parallel, whether or not the schematic "wires" are really traces or pours.

Distance from capacitor makes a difference, impedance goes up at high frequencies.  If a digital output suddenly turns on, and the capacitor is halfway across the board, the rise time will be much longer.  Such effects could cause glitches if voltages change enough to be LOW instead of HIGH or vice-versa.
 
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Offline newtekuserTopic starter

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Re: Power from trace vs copper pour
« Reply #3 on: February 04, 2024, 06:19:04 am »
Components are still in parallel, whether or not the schematic "wires" are really traces or pours.

Distance from capacitor makes a difference, impedance goes up at high frequencies.  If a digital output suddenly turns on, and the capacitor is halfway across the board, the rise time will be much longer.  Such effects could cause glitches if voltages change enough to be LOW instead of HIGH or vice-versa.

Excellent, thanks a bunch!!
 


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