About CIRCUIT LOOPS in switching converters

#128 In this video I look at how circuit loops and well layout in general have an impact on the magnetic noise emission of a boost switch mode power converter. I try out various constructions for the same schematic and assess how it impacts the performance of magnetic emissions.
Related previous videos:
Active load: • DIY - Constant current...
Current probe: • EMC debugging - Near f...
Loops in Amplifiers: • About CIRCUIT LOOPS in...
Circuit schematic: drive.google.com/file/d/1JoKX...
Datasheet: www.diodes.com/assets/Datashe...
Further reading: www.analog.com/media/en/techn...
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[@jamesm6951]

Your videos are so effective at drilling particular engineering concepts into my head. Don't stop making these, tati.

[@1828fernando]

Excelent!!! What happen if you use a PCB with ground plane?? Thsnk you!!!!

[@badscrew4023]

In my 30+ years doing electronics (including 3 years of EE uni courses!) I somewhat missed that inductance was proportional to the area! Great video :)

[@paulp1204]

I have to confess (conFesz?) I have been focussing entirely on trace length rather than enclosed area also. Really worthwhile video. Thanks Fesz.

[@jakobhalskov]

Nice new shirt! And very well explained; your 12 minute video did it better than my 4 month EMC course at University :D I am planning to do some electronics basics video myself, and yours are very inspiring for this :)

[@josip1881]

Its not new, i remember that yellow one it is strange, usually those are bluish, greenish :)

[@paulpaulzadeh6172]

very good channel and content

[@nbuzkila]

Another great video! Thank you!

[@felixcat4346]

Thanks for your post.

[@Graham_Wideman]

Great video really demonstrating actual examples of things many of us know to be true in theory, but may not have seen directly comparable good and bad examples in practice right next to each other. Thanks once again! .

[@KamleshGadhvana]

thank you very good video

[@electromechanics1]

Very good explanation sir and nice experiments thank you for good information

[@leiferickson3183]

Great demonstration!

[@maxpetrelli2142]

As usual great content! Thanks for your constant effort in spreading electronic knowledge :)

[@Julian_Kulenkampff]

Thanks, it was a very interesting measurement!

[@arslanbhatti9771]

awesome video, great examples, and well made :) . Always learn something new in your videos!

[@byronwatkins2565]

At 9:30, you can also replace the traces by twisted pairs for large current paths if HF noise is still a problem.

[@josip1881]

Are those FesZ Space cookies? :), thanks again for interesting video

[@R2AUK]

Thanks for the video. As a side note, I'm pretty sure DSA815 supports up to 3 traces, there is no need to overlap them on the computer.

[@FesZElectronics]

I think I played around with that function at some point, but the traces I used where "peak hold" or "average" - I didn't try saving and loading traces from memory, I will be doin that. I'm still learning how to use the DSA... Thanks for the advice!

[@R2AUK]

@@FesZElectronics Oh, I see. You can use peak hold or average, and then freeze the trace, and use the next one.

[@Samuel-km5yf]

Very nice video FesZ! A couple curious questions: What spectrum analyzer are you using? How do you fabricate your PCBs? (e.g. photo etch?) I love your content. Please keep it up!

[@FesZElectronics]

Hello Nick! I have a Rigol DSA815 and for PCB making I use the tonner transfer method - I covered this a long long time ago - kzbin.info/www/bejne/i5rFmX-tqcd1h7M

[@Samuel-km5yf]

@@FesZElectronics - Thanks for the reply! Your toner transfer video was very helpful.

[@falconhawker]

Would using a 2 sided PC board with a layout that insured the forward path was directly over the return path of the current , carefully located on the UNused side of the PC board reduce emissions ?

[@jgpeiro]

What about the noise difference with and without load of this dc/dc circuit? Could you share these measurements in a youtube short video?

[@lucabelvederesi6914]

Very nice video like always 👌 Should be interesting to see the behaviour with a 2 layers PCB that have a reference plane on bottom side. For example with GND or the DC voltages... and finally with a different PCB thickness??

[@FesZElectronics]

Thank you! I do plan to make a video on the impact of the ground plane, but I wanted to handle that as a different topic.

[@TechInventorAman]

Just to let you know that the third method of making the trace very near to each other will create an issue of crosstalk on the feedback pin

[@FesZElectronics]

I specifically didn't touch the feedback trace, just the main power stage. Anyway; if the feedback line is routed close to the ground trace, it should not have issues.

[@yancymuu4977]

Very informative. Thank you. I have an i2c circuit between two boards (about a meter apart) in an environment close to a solar array charge controller. During the day when the charge controller is handling a lot of power (lots of switching noise) the i2c link generates many glitches. I would enjoy a video on how to improve my setup.

[@jakobhalskov]

One thing I have learned is that I2C is not really designed or meant for connecting devices at a distance. It's original purpose was to interconnect components on the same PCB (or a very nearby module). But..! If you were to try to improve your setup I would look at the cables (twisted, shielded?), what I2C speed is used (400KHz vs 100 KHz or maybe going lower?), and the strength of the pull-up resistor (lowering the value will increase power consumption a bit, but make the signal cleaner). Alternatively consider another protocol like RS-485 which is much more suited for this task when conning modules across a distance in noisy environments. Hope this was a bit useful and I am sure mr FesZ has more great ideas! :)

[@FesZElectronics]

I have to agree with Jakob! I would add though that you could put some RC filters on the lines, something to cut frequencies above the intended data rate - 100R+100pF to start with. The series resistor though must take into account the pull up resistor - you must make sure the voltage divider created does not run the initial functionality.

[@yancymuu4977]

@@jakobhalskov I will try all of these suggestions. I just changed the software on my esp32 to run the I2c at 10khz vs the default 100khz. Will see how it performs later today. I also have some shielded cable with two conductors and will make a new cable with the clock and data inside the shielded cable. I'll save the pull-up change for last as that would require some disassembly and soldering.

[@yancymuu4977]

Thanks Jakob. I have added that to my list of trial solutions.

[@omeridan8815]

Why didnt you use a ground plane??

[@gwc1410]

This is a very good video, and well timed for me. I was just wondering about RF shielded boxes recently (like your Fesz cookie box). Does it matter what it's made of? Such as steel, tin, copper, etc. How tightly does the lid have to fit? What about the hole for the cables? I would think a feed through connector would be best. Again, thanks for another excellent video.

[@FesZElectronics]

Hello! I covered this to some extent - the material matters because of its skin depth and the frequency at which you wish to use it - to improve magnetic shielding, especially at low frequency steel is recommended, but at high frequency copper is also good (video about magnetic field shielding kzbin.info/www/bejne/aIaUoGlsl9iSh8k ) and to improve electric field shielding an all around low impedance connection is mandatory - so the contact area needs to be clean and ensure good contact (more on electric field shielding: kzbin.info/www/bejne/ianUkmqEYsuofq8 )Regarding the access holes, these are capable of carring noise into the box - as could be seen in this video; commonly for supply lines some form of filter is usually built into the hole - as you mentioned a feed through connector with some built in capacitors would be ideal.

[@AdityaMehendale]

Agreed that you have a single-sided PCB and this brings limitations, but would it be a nice addition to consider a "type4" PCB where you have traces that emulate a _twisted pair_ (so that some loops run clockwise and others run counterclockwise)? You could reduce inductive coupling to almost zero.

[@Graham_Wideman]

PCB "twisted pair" is nice for traces that you want to protect from receiving interference. And in principle it would reduce emissions _from_ power traces. However, the problem with turning power traces into twisted pairs is it involves a lot of vias, and those are relatively high resistance.

[@AdityaMehendale]

@@Graham_Wideman True, unless the component is used to "bridge " the trace.- kinda' like a "clover" in highway-intersections.. Else solder-filled through holes :)

[@paulhome2023]

Thank you for the Video. Really interessting like Always. I wonder If you could do a comparison between shielded and unshielded inductor

[@paulhome2023]

And a question how did you solder on this Boards Looks interessting

[@FesZElectronics]

Thank you! Already did the inductor structure comparison a while back - kzbin.info/www/bejne/m6vWoZeXqtKoZ9k

[@paulhome2023]

@@FesZElectronics thank you for the Link to the Video. Maybe again the question how did you do these Boards ?

[@FesZElectronics]

I'm not sure what you mean - the boards where made and assembled "by hand". To make the boards I use toner transfer method, and to assemble, well, a lot of patience

[@iwbnwif]

@@paulhome2023 if you want to know how the boards are made, watch this video kzbin.info/www/bejne/i5rFmX-tqcd1h7M

Great video! What about groundplanes?

[@FesZElectronics]

Ground planes will of course help by reducing inductance and noise further; I just did not add them to separate topics a bit. I will try to analyze those also in a future video.

@@FesZElectronics thanks! Im really looking forward to this video!

[@objection_your_honor]

Galvanized metal trashcans, grounded with heavy gauge wire to a ground rod, is a cheap and effective way to shield against EMP or other EM radiation and electrostatic. A favorite of doomsday survivalists. They put their emergency communication equipment in it. No ground, no deal :) Would grounding the supply to the metal not be enough to shield the electronics inside? Like how a car battery is wired.

[@clawsneutron7155]

Hey, pls try boost converter...thanks

[@FesZElectronics]

This was a boost converter...

[@ahbushnell1]

Add a ground plane