VDD on PICs

camerart · Aug 13, 2018

Hi,
Some PICs have 2x VDD and VSS PINs.

Is it ok to connect sets of PINs using a TRACK under the PIC instead of an individual external TRACK.

Camerart.

Pommie · Aug 13, 2018

Why wouldn't it be OK?

Mike.

camerart · Aug 13, 2018

Pommie said:
Why wouldn't it be OK?

Mike.

Hi M,
A question answered by another question
C.

Ian Rogers · Aug 13, 2018

Yes!!! That's how I do it.. AND!! the trace moves on and powers other devices as well..

camerart · Aug 13, 2018

Hi I,
That's what I've been doing, but wanted a second opinion, thanks.
C.

rjenkinsgb · Aug 13, 2018

It's fine, just make sure you have adequate decoupling as close as possible to the PIC.
If anything, that can be more important to avoid problems.

Also, keeping power and ground close together under each IC helps reduce inductance so lowers noise more.

dknguyen · Aug 13, 2018

Sure hope so since that's what a powerplane is.

JonSea · Aug 13, 2018

The important thing is that ALL power and ground pins be connected. They are not optional.

dknguyen · Aug 13, 2018

JonSea said:
The important thing is that ALL power and ground pins be connected. They are not optional.

Not to each other though.

camerart · Aug 13, 2018

dknguyen said:
Sure hope so since that's what a powerplane is.

Hi D,
Will you explain what you mean please?
C.

dknguyen · Aug 13, 2018

camerart said:
Hi D,
Will you explain what you mean please?
C.

You know how you dedicate a ground plane on a PCB is? A power plane is the same thing but for power.

JonSea · Aug 13, 2018

dknguyen said:
Not to each other though.

I thought that point kind of went without saying

camerart · Aug 14, 2018

dknguyen said:
You know how you dedicate a ground plane on a PCB is? A power plane is the same thing but for power.

Hi D,
Of course, rather obvious really.
C.

camerart · Aug 14, 2018

JonSea said:
I thought that point kind of went without saying

Hi J,
In normal circumstance that's true, but with me it needs saying got it now.
C.

JonSea · Aug 14, 2018

You may find this a good guide to avoid common problems when using 16F or 18F PICs. It's based on reading many forum posts and observing comnon problems:

Commandments Fou Using PICs

camerart · Aug 14, 2018

JonSea said:
You may find this a good guide to avoid common problems when using 16F or 18F PICs. It's based on reading many forum posts and observing comnon problems:

Commandments Fou Using PICs

Hi J,
I normally follow most of those commandments although I usually only have one 0.1uF Cap/PIC
Thanks, C.

dknguyen · Aug 14, 2018

camerart said:
Hi J,
I normally follow most of those commandments although I usually only have one 0.1uF Cap/PIC
Thanks, C.

That won't work on chips with more horsepower.

camerart · Aug 14, 2018

dknguyen said:
That won't work on chips with more horsepower.

Hi D,
Ok.
C.

Nigel Goodwin · Aug 14, 2018

camerart said:
Hi D,
Ok.
C.

I think he's been rather pessimistic, obviously you need something more on a 50W power amplifier, but for a processor you're be hard pushed to need something larger nearer the chip.

dknguyen · Aug 14, 2018

Nigel Goodwin said:
I think he's been rather pessimistic, obviously you need something more on a 50W power amplifier, but for a processor you're be hard pushed to need something larger nearer the chip.

It is poorly worded. I think the author is just saying don't omit the seemingly vanishing, tiny capacitors.

Myself, I was talking about the number of tiny capacitors per power pin.

VDD on PICs

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