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Electronics => PCB/EDA/CAD => Topic started by: NickWolfe on February 23, 2019, 12:35:16 pm

Title: What is v1p1
Post by: NickWolfe on February 23, 2019, 12:35:16 pm
Hi guys, new forum member, years of eevblog watcher here

So I'm about to design my first pcb, and in the reference I am seeing labels such as v1p1, v1p3, v3p3 that runs out to nothing (unconnected) what might this mean? I have spent the last two days searching for an answer to no luck.

Thanks in advance!
Nick
Title: Re: What is v1p1
Post by: NickWolfe on February 23, 2019, 12:40:59 pm
Sorry for the bad quality photo, but thought it'd be good with at least a hint as to what exactly I meant
Title: Re: What is v1p1
Post by: ebastler on February 23, 2019, 12:43:40 pm
I guess V1P2 means "Voltage 1.2", V3P3 is "Voltage 3.3" etc..
You should see a source for these voltages somewhere on the schematic.
Title: Re: What is v1p1
Post by: Twoflower on February 23, 2019, 12:48:08 pm
I agree with ebastler.

But you should find the source of this. Somewhere in the schematics should be the other end if this signal/supply. It is just a label to simplify the schematics otherwise you have to draw everything on one page and have a lot of lines running across. This could also be on a different page.
Title: Re: What is v1p1
Post by: NickWolfe on February 23, 2019, 02:21:04 pm
Looking at this, it makes sense, I didn't bring a reference sheet with me, only datasheets. Tried my best to frame what I meant in the picture.
Also thanks a ton for the swift responses!
Title: Re: What is v1p1
Post by: NickWolfe on February 23, 2019, 02:22:58 pm
Choosing a highspeed bga as a first project might not have been the smartest choice  :palm: but this can change the future of gaming, so...  ;D
Title: Re: What is v1p1
Post by: NickWolfe on February 23, 2019, 02:24:43 pm
Quickly, if there's an experienced fellow that can set aside som time in private for some help or guidance, I'll make it worth your time
Title: Re: What is v1p1
Post by: Doctorandus_P on February 23, 2019, 04:20:27 pm
ebastler is probably right, but engineerd do not trust "probably"

But the solution is simple:
V3P3 is a label. and labels with the same name are connected together.
The circuit looks like a power supply, (Engineers, don't trust "looks like", but they can take a hint).

So to be sure, just search for all other labels with the name V3P3.
Title: Re: What is v1p1
Post by: NickWolfe on February 23, 2019, 04:28:12 pm
Yeah, after trawling through a ton of pages in two different datasheets, that gives the most sense. Let's see how bad it blows up when fabricated. (it's a damn $30 chip)

And yeah, the schematic is for the power delivery part of it, the chip is split in to 3 seperate parts in the schematic just to confuse me even more, and this is the power part.

Shivering just thinking about the headaches awaiting when I have to lay it out, with differential pairs, matched impedance and all that across 6 layers *fml* XD

Sendt fra min SM-G930F med Tapatalk

Title: Re: What is v1p1
Post by: NickWolfe on February 23, 2019, 05:20:49 pm
Bingo! Found this referenced to the vxpx question.
Thanks for all your help! (https://uploads.tapatalk-cdn.com/20190223/a407fa8d02160698713c0ca4b9c24dbb.jpg)

Sendt fra min SM-G930F med Tapatalk
Title: Re: What is v1p1
Post by: asmi on February 26, 2019, 02:18:26 pm
I always mark my power rails like +1V0 (1.0 V), +1V8 (1.8 V), or add some specifier if there are multiple rails with the same voltage (like +1V8_A for "quiet" 1.8V rail for analog devices).