EEVblog Electronics Community Forum
Electronics => PCB/EDA/CAD => Topic started by: louislouis on December 15, 2024, 08:37:38 pm
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Hi,
I'm trying to design a 4 layer pcb with:
-XL6008 based buck boost converter on one side (fixed to 12v output)
-XL4015 based buck converter on the other (fixed 5v output)
Keep in mind I'm a beginner and learning pcb design online as I go.
I was planning of having 2 ground planes in the middle but are there other things I need to consider as the 2 converters will be really close? Will there be any interference? I have to place them on either side as the pcb will be quite small 50x80mm and I have other stuff on the buck converter side (Attiny control IC with status leds and buttons).
Also I don't really know how to place the two inductors for the XL6008 buck boost converter.
I have the schematics from the ICs datasheets:
https://www.lcsc.com/datasheet/lcsc_datasheet_1809200019_XLSEMI-XL6008E1_C73012.pdf (https://www.lcsc.com/datasheet/lcsc_datasheet_1809200019_XLSEMI-XL6008E1_C73012.pdf)
https://www.lcsc.com/datasheet/lcsc_datasheet_1811081616_XLSEMI-XL4015E1_C51661.pdf (https://www.lcsc.com/datasheet/lcsc_datasheet_1811081616_XLSEMI-XL4015E1_C51661.pdf)
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Thank you for your time
UPDATE 1:
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So after some digging and seeing your answers I've tried fitting both converters on the same side of the board. I tried to place the components the best I could (inductors away from FB line, keeping the loops small and tight).
For the buck boost I couldn't find an easy to buy coupled inductor (designing on easyEDA, buying LCSC and JLCPCB), so went for two separate inductors. I read I lose in efficiency, is that all?
The input is a 3S lipo.
output load is around 3A minimum for the 5V and 2A for the 12V.
There is also a mosfet setup for an emergency stop between the lipo input and direct output (goes to 20A UBECs)
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What voltages and currents will be used?
The "two inductors" for XL6008 are coupled inductors, you can read here: https://www.coilcraft.com/en-us/edu/series/a-guide-to-coupled-inductors/ (https://www.coilcraft.com/en-us/edu/series/a-guide-to-coupled-inductors/)
I doubt the attiny will have issues, unless, you are working with analog signals, then you need to take care.
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Note that if you plan to reflow the PCB in an oven (or have it produced commercially that way), you may have problems soldering heavy components like inductors on both sides of the PCB unless they are glued to stop them falling off.
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You may want to tie the SW nodes of U2 together, might not work as drawn.