Electronics > Beginners
Why am not able to get a grasp of PCB designing?
redgear:
--- Quote from: james_s on November 14, 2019, 05:16:36 pm ---The maximum voltage across the resistor. This of course depends heavily on where it is used, in most cases the power will be very low except for resistors used for current sensing and such.
--- End quote ---
Ok, so I should calculate the power rating of each resistor.
Just to check if I am doing it right,
The resistor R11 on USB C is 10k. The maximum voltage it will see is 12v. The power rating of the resistor using the formula P=V2/R gives, 1/100 Watt. Is that correct?
How do I determine the power rating for the resistors where I'm not sure about the voltage it will see, like the current sense resistor or the R2 114k on the RSET pin?
Thanks
redgear:
--- Quote from: tautech on November 14, 2019, 09:03:32 am ---Yes. :)
First thing I spotted, top 2 resistors by the switch....rotate them vertical for better connectivity/easier routing.
While the purists like every device group orientated the same sometimes it's easier to flip and swap to make for easier routing.
Apply similar thinking throughout the PCB and you'll be staggered how much easier things become.
Shift some component designators off the device so it's easier for us to pick a # that should be moved/flipped etc.
Stack
them
alongside
somehow
like this. :)
--- End quote ---
Done. Here is a picture
Any more suggestions?
Edit : After taking the pic, I rotated the resistors R5 and R9 to make connections easier.
ebastler:
That latest placement looks pretty good, I think. Only change I would suggest: Give yourself a bit more room around the main IC by making the PCB larger in the vertical direction. The passives above and below are very close to the IC, so you might run out of room for the traces. You can always push things closer together later -- while I have not used KiCAD, I read that its push-and-shove router works quite well.
Time to start the routing! (Which will probably lead you to some more tweaks in the placement once you look at the routing details.)
tautech:
--- Quote from: redgear on November 15, 2019, 05:11:19 am ---
Edit : After taking the pic, I rotated the resistors R5 and R9 to make connections easier.
--- End quote ---
:-+
--- Quote ---Any more suggestions?
--- End quote ---
Lots, really lots.
More of the above, much more.
You are gaining the vision required but keep looking and looking and after an autoroute of two you will see more. Pick a net or two and focus on getting them the best you can the rinse and repeat with other nets.
At a glance a few simple pointers.
Flip and lower D6 so to run the GND trace around the top to J3.
Flip TH1 and R8 then you have just one trace to sort out the routing for and lift it a little and run the trace along the edge of the board.
Move Q2 to between Q4 and U1.
Consider rearranging Q1-4 and associated components to allow for easier/better routing.
Don't bunch SMD passives too close to bigger components. (later you'll thank me. ;) )
Tidy up labeling even though after routing you may need to do it again. Use same font size for all.
That's an hour of two's work to sort out and enough for now so to not piss you off too much. :)
redgear:
I really appreciate you taking the time to guide me. Thank you so much.
--- Quote from: tautech on November 15, 2019, 07:09:55 am ---Consider rearranging Q1-4 and associated components to allow for easier/better routing.
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I planned to keep all the power FETs in one section. I will try rearranging it.
--- Quote ---Don't bunch SMD passives too close to bigger components. (later you'll thank me. ;) )
--- End quote ---
Are you talking about the capacitor networks? Aren't they supposed to be as close as possible to the ICs?
And the LEDs, I cannot rearrange them since I planning the mechanical enclosure to have LEDs at the center.
--- Quote ---Tidy up labeling even though after routing you may need to do it again. Use same font size for all.
That's an hour of two's work to sort out and enough for now so to not piss you off too much. :)
--- End quote ---
Ok :-+
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