Questions about 4-layer boards photos

Thread Starter

SiCEngineer

Joined May 22, 2019
299
Hi all, please check out the 4-layer board contained on page 17 of the following> https://www.ti.com/lit/ug/snou140a/...ps%3A%2F%2Fwww.ti.com%2Ftool%2FLMG34XX-BB-EVM.

It is for a daughterboard card from Texas Instruments for a half-bridge GaN power stage. I am finding it quite confusing for the following reason: It looks as though some of the figures are flipped? If you look at figure 16 and 17 for example, the third and fourth layers of the board, the location of the 6-pin jumper has switched sides. It looks like the first three layers are in sequence and aligned correctly whereas the last layer has been flipped. Does this seem to be the case? Is it common practice to show the outer signal layer flipped w/r/t the first signal layer, if so why?
If not - is this something you've not see before and is there any easy way to make this board easier to follow and copy?

Finally, what are all the vias for? Do these vias make connection between the top layer where the VCC and GND is connected and pass it to the respective VCC and GND copper layers via the vias? I also believe the vias on the switches are for heat sinking - are these passed to the VCC layer or the GND layer for heat dissipation, or does it not matter so much?

For context, I need to design myself a GaN board. The only difference is that I need a two-switch forward converter and therefore I need to slightly redesign the board. I don't know how else to do this so I plan to just build the board up in Altium as a schematic and then PCB and break the Vsw node. I don't think this will be a massive difficulty if I follow the board design well..?

Thanks for your help in advance!
 

Thread Starter

SiCEngineer

Joined May 22, 2019
299
Hi SiCEngineer,

Did you check the design files?

Maybe it's easier to follow the layout through the gerber files.

Best regards,
I actually was trying to download the Gerber files but for some reasn I’m really struggling to get them to load in my Altium software, for example it gives errors such as the design file is out of bounds I think it was? I’m not currently able to check.

is it relatively easy to take the gerber file and slightly adjust it so that I can move/disconnect/split the switching node, add capacitors and diodes to the board, etc?
Thanks for your help!
 

waulu

Joined Dec 23, 2016
59
I never used Altium. But when I mentioned gerber files I was talking about the PDF that I attached in post #2.

With the Gerber files you can only inspect the layout, not change the layout. The gerber files are used by the PCB manufacturer. If you have the design files for Altium, then you can change the layout.

Regards,
 
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Thread Starter

SiCEngineer

Joined May 22, 2019
299
I never used Altium. But when I mentioned gerber files I was talking about the PDF that I attached in post #2.

With the Gerber files you can only inspect the layout, not change the layout. The gerber files are used by the PCB manufacturer. If you have the design files for Altium, then you can change the layout.

Regards,
That is why I am drawing the schematic and PCB again, because I can’t seem to get hold of the actual design files for Altium but only the gerber files. I will take a look at the gerber files tomorrow. You say these will be a lot more useful for me to understand the layout? It is quite perplexing to me - there are multiple power supplies of different voltages yet only one power plane. I would assume you need a power plane for each power supply voltage and separate Ground plane for all of the grounds of those power supplies so that they are not electrically connected and that the ground currents are not shared between supplies. But that doesn’t seem to be the case here.
 
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