Hi, I am trying to create my first PCB and it is a buck converter that will draw 12A during full load. I checked internet and they recommend 8 mm trackwidth for this current rating. But when I use a 6mm track and draw it out of the mosfet it can not even exist as in the figure. What is the logic behind this what should I do if 12A passes from there ?
Draw zones instead of tracks.
Also make sure to follow manufacturer’s layout recommendations.
Can you show a visual if possible so that I can understand how should it look like?
I do not know what is your device shown, and I do not know what are the voltages involved.
But FWIW it seems likely that there is nothing wrong with the layout portion as shown in your image.
I agree. But the other option is to increase the track width as you get away from the device and as space permits.
Three options
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you can JUST about manage an 8mm track but this is 100% creepage dependant and I personally would not recommend it and while the mpt037n08 is a 10V FET… still…
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thinner track to break away then beef it up and rely on the heatsinking of the thicker track to keep the stub cool
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zone to give you the freedom. This is my recomendation and I do this all the time for alot higher currents
Your fill have to have different net specified.
It would be helpful to give your name to nets that you plan to make as filling zones.
I really couldnt understand what you said
make sure the net of the zone matches the net of the pad (in this case Net-(D6-A)). Also press “b” to refill.
I will typically name my nets for area’s that I use zones as it makes zone management easier
I don’t know what thickness of foil you are using, but for example, for 35 microns, you can use not one wide track, but several smaller tracks, for example 1.5 mm, which is equivalent to a current of 4.3 amperes.
In addition, the use of thermal relief allows for better soldering of components during production. Of course, there are cases when you can’t do without a solid fill, but this is rather an exception.
I cannot find that at Digikey. If I Google it I do find some hits but nothing that I would immediately trust for a reliable datasheet. (??)
Motorola > ON Semiconductor used to prefix many MOSFETs with “MTP” so my first thought was that “MPT” might be a “tpyo”…
First sentence: When adding your fill you specified different net than the net of pad you want to connect to, so as they are different nets KiCad keeps clearance between them.
Second sentence: When selecting net for fill it is easier to find net that you gave it a name than to select among net names KiCad gave to nets. Your can be for example “Out” why KiCads looks like you see (Net-(D6-A)). If there are lot of such nets it is hard to find right one.
Simple action:
Make sure that “zones” are checked in the selection filter at lower right.
Right click (context menu) select the zone.
Properties
Select Net (D6-A)
Reflow the zones (“B” hotkey).
Use heavier copper, and use both front and back sides.
@BobZ, my MOSFET doesnt have a net for that pin my nets are only voltage and gnd nets (like 3v3 12v EN D+) etc. So that (Net-(D6-A)) is not even listed under the nets
What is your KiCad specific question ?
This forum is here to help with KiCad . . . not just generic Electronics questions.
Adjusting thread close time.
If at schematic you place label on the wire you give this net your name.