Every Component of a Switch Mode Power Supply Explained
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- เผยแพร่เมื่อ 31 ก.ค. 2024
- In this video we go through every component of a modern switch mode power supply taking a look at their function. The first half of the video is dedicated to understanding how inductors are used in these circuits, as these are the beating hearts of power supplies. The second half of the video runs through each component, with increasing complexity, highlighting their position in both the schematic and the physical circuit before delving into their purpose.
What happens when:
0:00 Introduction
0:31 Evolution of switch mode power supplies (1980-2022)
1:47 Using inductors to store and release energy
3:40 Using inductors in a switch mode power supply
9:47 How inductors keep shrinking
11:35 Introduction to circuit analysis
12:00 Simplest possible SMPS
14:31 Output indicator LED
14:49 Additional output filtering
15:19 Output capacitor bleeder resistors
16:01 MOSFET source current shunt resistors
16:37 Input filtering
17:52 Input protection
19:54 Class-Y capacitors
20:35 Snubbers
21:47 Additional components (controller)
22:06 Conclusion
22:40 Outro
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Hi everyone, I've had several comments about the lack of a section going through the controller circuitry, this was intentional in an attempt to keep the video simple and digestible by focusing only on the "power" components. There will be videos coming soon on PWM control and MOSFET gate driving, though I should have mentioned this in the video and still given a brief overview of the circuit, so sorry about that. Thanks for all the nice comments!
I'll look forward to those. As an electronic engineer (a while ago) dealing with the digital stuff I was always a bit concerned that I didn't know enough about switched-mode supplies so this was great. Would love to see how the MOSFET switching frequency is determined and then implemented though. Great work 👏
Yeah, I was just about to ask about that. I look forward to the videos explaining those parts of the SMPS circuit. I do hope you will continue to use the same power supply from this video to explain those topics; you know, to keep the continuity (wait, does that count as an electronics pun). Thanks for the the clean and clear explanation.
Well done, I came looking for someone else asking about the control circuit and found this. Looking forward to the sequel. Well done otherwise.
@@Budreaux1973 Certainly does count as a pun :) I probably won't use this to be honest as I want to be able to show live demos which is a lot easier with a custom system, I may show this at some point though.
10:21 Nice shoes! 😉
On a more serious note: Really excellent explanation of the fundamentals of an SMPS.
I’ve watched many (too many tbh;) videos with the same topic and yours is the best, by far I may add.
Thank you!
I'm a 50+ year old electronics graduate and lifelong hobbyist and I have to say this is one of the very best explainer videos I have ever seen. I know how switch mode PSUs work but I still felt as if I learned a lot due to the approach taken. You are a natural educator with an engaging personality, eloquent and clear delivery, and an enthusiasm that shines through. Stripping the circuit back to basics and using the mechanical spring analogy will help a lot of non EEE folks grasp this topic.
This is the first video of yours that I have watched but it certainly won't be the last. Keep up the good work, and thanks! 🙏
Totally agree 👍
I'm very new to all of this. I feel like I got a grasp of the basics.
I did electronics way back in the late 1980's but never really understood all of it. Video's like this help the understanding.
Thank you so much! Reading feedback like this really makes it all worth it :)
my first video of his as well. First of many
I’m almost 70 years old and I’m industrial electronic technician. I found you to be a genius. Thank you very much. Joe
As a 76 year old electrical engineer, I found this Brilliant!
Thank you!
Brilliant was my feeling throughout the video. Your pedagogic style is effective and empathetic. I hope academia takes note.
How many years I have been looking for someone to just plain and simply walk through a circuit like this. Thank you.
This is the only video i have ever watched fully clearly explain all the components of the switch mode power supply in my life.
That was the best explanation I’ve ever seen in decades of being a tech.
I wonder how the control circuit looks like and works. The whole thing is just a brick without it.
@@Oktokolo yes, he should follow up with that for people.
I really like the way you built up the schematic by starting with the basic layout and then adding components to describe the complexity. By so doing, you effectively started with the foundational components and built on that. Well done!
Thank you! It took a while to edit it all nicely but was definitely worth it.
@@electrarc240All that scripting, recording, re-recording and editing is much appreciated!
I’m looking forward to the video where you’ll explain why those GaN power supplies can be so small yet powerful. (In due time)
@@electrarc240 Maybe the things omitted in your narration, such as the optron and control chip, are also worth explaining. I've got a broken led strip driver and already blown a USB scope and a PC it was coupled with in trying to make the driver work, but I still have many unblown things to blow (throwing the driver into trash would solve the problem, but such a simplicity is for losers), so I must learn every aspect of the SMPS before I run short of unblown things. And your video is the best I've seen before in that respect.
P.S. I'm even less English guy than that wantan3_6_0 dude from the other comment is, but yet hope the letters written above are at least resemble proper English.
@@electrarc240very nicely done! Only suggestion I might have is that the black on green is tough to see, so maybe think about some higher contrast colors or just black and white. Otherwise loved the content!
Yes, that gradual buildup from simple to real of the schematic was an excellent teaching tool. And I found out I didn't know as much about switching power supplies as I thought I did. 😁... But I do now! (almost)
But really, great job, you're an excellent teacher.
As a ham radio op….. those “annoying” emc components are a thing of beauty!!!! This was probably the best explanation of SMP PSU’s I’ve seen - bravo!
Wow thank you so much!
@@electrarc240it really is fantastic to have RF quiet devices
You beat me to it, personally I reckon they are the most important side of things.
Ham here too and its all the cheap n nasty consumer electronics out there that is destroying my hobby.
Currently have a neighbor with 5x split systems and any one of them wipeout all of my operating bands.
I remember when I was trying to make a simple clock circuit for a 10Mhz CPU , I didn't knew about PLL and it became an antenna "by mistake". Thank god nothing important is at 10Mhz, right ?
(well, it was just a 1w signal)
Yep. Used to repair a lot of SMPS supplies to component level. Used to see filter caps fail a lot and occasionally, pop the zener reference or optocoupler in the feedback circuit, which would then allow the drive to runaway and increase output, failing additional filter caps.
A good curve tracer could save the day if the zener was starting to fail, the rest it was simpler to replace the filters than to run around disconnecting the filters and checking ESR. The cost per component was cheaper than the man-hours spent testing them anyway.
Never had anything in the snubbers fail, did have the EMI caps occasionally fail.
Loads of techs had trouble figuring out how these rather simple circuits worked and failed. Interestingly, those that couldn't figure them out also couldn't figure out a PLL. That caused me to joke that they were refractory to proper feedback.
This type of explanation is what I need to see. Often, an instructor just buries you with theory. It becomes overwhelming, and my brain just turns off. Thank you for taking the time, and I welcome further videos.
I've always felt buried- but knew it was simple and this guy knows how to explain it!
I'm a 77 year old retired electrical/electronic engineer and my education was obviously back in the days of poorly written books, chalk boards (as classroom visual aids), and sliderules. I couldn't have imagined the ways we teach nowadays, and I am so impressed with the way you described this power supply by starting with the basic circuit and then explaining why all the extra parts are needed. Excellent!
Exactly
Some of my early education over AC theory involved WW2 era 16mm films!
Black and white classified training films using billiard balls on sand to illustrate conductivity, current flow and valence shells!
This material here is sensationally well executed. I don't believe I've encountered a better, more engaging approach than this.
Superb
Considering how for we've come, imagine what's right around the corner.
Thank you
Much appreciated
I am what people normally called "dumbass with a tool's " its means I have or can have any tools but to stupid to do anything with it. so I'm just poke something around until it's either broke or blown. your video and explanation are really godsend to me because English are not my mother tongue yet I can follow what you are explaining...keep up the hard work man....
Wow thankyou very much! I try hard to avoid using the long "show-off words" that I find to be very common place in engineering because I'm not trying to prove anything I just want as many people to understand these cool things as possible!
Yeaa... :( i feel you bro...
I'm with you. Love math and science, finished my trig book on my own ahead of the class, used to be able to solve basic electric diagrams. Can't solder a wire to save my life.
@@woodstream6137Throw the conical tip that probably came with your iron in the trash, get a few sizes of compatible bevel tips and thank me later.
As a computer engineer and power engineer, I liked your explanations and demo of increasing the frequency so that you can reduce the inductor size but with limits due to the heat, spillage in your case 🙂
It's been almost 50 years since I sat in a classroom and had one of the best instructors at the Sears Technical College explain the new switching power supplies most new portable tv's would be using. He used a blackboard to do the same type of visual association of circuits that he was lecturing on. You have the same dedication and enthusiasm and have earned my respect! Keep up the good work.
Thank you!
It does my heart good to see a bright young person explaining electronics so well.
I started studying electronics since 1983 or so. Yes - we have come a long way.
Bravo!
Where were you back in the 70's when I needed you?
Impressive. Refreshing.
The best explanation of SMPS I've ever seen so far.
Same here!
Thank you!
I've studied and worked on electronics for the last 20 years and this video finally clicked in a couple of concepts that had been banging around in my brain for years regarding smps. Hands down the best switch mode power supply video on TH-cam.
Subbed
Wow thank you very much! Glad I helped fill in those pesky gaps
From what I remember from my electronic studies, I have the impression we spent too much time on manually analytically solving circuitry, spending hours on differential equation solving on very trivial circuits (one transistor, a capacitor and two resistor is enough to make it quite hard to solve), a thing that is way better done by computer software simulation, and not enough on this higher scale functional diagram like in this video, that seems actually way more useful to actually understand stuff 🙂
@@ThomasKundera As a current student I couldn't agree more, it's such a shame
@@ThomasKundera I saw the reference to diff eq and I had a flashback to the nightmare that course was in college as an undergrad studying computer science. I did fairly well in all my other mathematics classes but I could not wrap my head around DE and I failed the class my first time take it. i'm not even sure how I (barely) passed when I took it again the next quarter. I think it was so traumatizing that my brain has blocked out all memory of those classes. I'm feeling anxious just writing this and its been like 25 years since I graduated. ugh.
I sat through watching the circuit building up for 20 minutes and I feel I could watch it for another 20 minutes as I've never got lost anywhere.
That is one impressively easy and coherent explanation.
The algorithm "thought" i might like your videos and boy, was it right! Well done. Can't wait to have time to watch more of your videos!
I have learned more within 20minutes of watching this video than I have learned in 20 lessons in electronics class. Great video!
Yeah and I learned more about fluid dynamics from taking a shower than 4 years of physics at the university. This was a refresher course for people that already knew what these components are, how they work and why they are in the box. It was enjoyable because instead of giving a test, he just read all the answers and you recognized what he said. Nothing new, just well presented. He left out a lot.
Wow I’m an electronics guy and this video is a masterclass for anyone interested in learning and understanding electronics! Saved here and will be sending this link to lots of people when trying to explain something. Very very easy to digest, amazing
Thank you very much!
I really like the way you broke it down to the most simple possible circuit that could work and then added on the extra components sorted by function. That made it far more digestible.
"Know what I like about you, you know about the system and your coherent with your explanation(Very Smart). I like your plan diagram and your input on each device. Know that you are appreciated." 👍
Thanks!
BRAVO Sir!
I failed out of electrical engineering 30+ years ago. I have a successful career in IT systems, but always wanted to know how the circuits worked. Looks like I have a new favorite place to watch.
I send my highest respect from Canada.
Thank you very much!
I have been an electronics enthusiast for 10 years now focusing heavily on SMPS design things although your analogies where very helpful, this video is simply brilliant.
Wow thank you so much! I'm always a little afraid of "experts" seeing my videos haha
@@electrarc240 meh, most barrels do have two bungholes. Some simply forget that one's for airflow and the other for useful product flow.
Hello, I made the first prototype switch mode PSU in the very early 70s for a now, long extinct company called APT at West Byfleet.
When I say that I made it, I mean that an engineer gave me a circuit diagram with a box of bits and a lump of plywood to mount it all on. The engineer was entertaining and rather frightened of his creation and would try to get others to turn it on for him, if he failed in finding a sucker he would use a broom stick.
At times when he had the thing running, you would get the odd person walking past bang his bench and send him through the roof which, was an understandable reaction; as a capacitor would occasionally explode showering the place with metal foil.
One of the few times in my life when I didn’t feel like I was working.
Happy days!
I'm gonna say this , this is probably THE BEST EXPLANATION VIDEOS I HAVE EVER SEEN ! I hope you were my teacher during my school days
Ahah thanks a lot I really want to be a teacher one day! Maybe that day has already come 🤔
Extremely well made, thorough, well-spoken, good order, good background info to prime us. I’ve seen very few instructional videos better than this. Kudos.
Amazing how you explained the power loss as water leakage, Thanks for the great Contant !
Haha I thought of that as I was watching the footage back, it seemed too good to not add in (and pretend was intentional). Thanks!
Inductors as springs, an excellent analogy, and the two buckets, brilliant. I have spent much of my career working on SMPSUs in one way and another, this was a truly excellent introduction. It can be hard to believe how ubiquitous SMPSUs and variants are, they are in every aspect of modern electronics. Thank you
The way you started with the most fundamental components in your schematic and built up the complexity was simply genius!! What a clever way to go about it.
As somebody who spends a lot of time drawing electrical schematics myself, i can tell you put in a lot of work just into the drawing itself (and obviously into the rest of the video as well).
What an amazing video overall. Instant sub. Please keep up the great work.
Thank you very much!
I learned more about electronics and circuit design than I expected. So much information packed in this video with simple and comprehensible explanation, great job. Can't wait for the video about how the controller circuit works.
2 years ago I had a strong curiousity about phone charger and also was looking to diy one solar DC charger and ended up deep in the rabbit hole trying to understand these. I always thought I should have wrote a blog post to analyze what I learned and share also but never did so I'm glad to stumble on this amazing refresher better than anything I would have written! Thanks
From Here.
Being an electrical engineer designing these monsters too: I congratulate to this clear explanation. Well done!
After taking a second look at the video, I think it delivers everything that is promised in the intro, and it seems to be downloadable. I think there are good reasons why all these designs need to be in public somewhere. Residences across the USA depend on similar devices to not catch fire every day. Some people have 12 of these things plugged in 24 hours per day. I did get distracted and confused by the spring, and the buckets. Thanks again.
This is now my essential SMPS explainer, will always point people towards this
All of the other comments are spot on. Just wanted to say thank you for exceptional content. One of the best electronics explanations I've ever watched, and I've watched hundreds, if not thousands!
Wow thanks so much!
That was the best description of a switched mode supply I’ve encountered. Nice one!
I've been working with electronics my entire life, especially in the Ham Radio world. This was one of the best explanations of how a switch mode power supply works. Bravo, well done!
I think if you watch a few Big Clive videos you'll see that there is an alarmingly large number of appliances from dodgy parts of the world with poor or non-existent isolation!
This is the first thing that comes to mind with modern electronics. All these huge corporations trying to continuously cut costs in a race to the bottom, and what suffers? Safety, reliability, customer satisfaction. But they only care about quarterly profits. It's disgusting what the world has become.
@@grabasandwich Completely agree, it is very unfortunate. There are still plenty of high quality products being made, just not for consumers as we just aren't worthy...
Watch DiodeGoneWild videos about USB chargers that are ‘dodgy’ and ‘super dodgy’.
If you like BigClive and this channel, you’ll probably like DiodeGoneWild too.
Let me know if you do ;)
I got a nice jolt from the plug of a fluorescent light fixture a few years ago. I touched the prongs right after I unplugged it. I made sure not to do that again.
@@SwapPartLLC I always find myself doing this to check PSUs when I unplug them, definitely not wise as you say haha
WoW!! I knew the basics of switching supplies but this was quite thorough examination of essentially all the components of a commercial supply! I learned a lot!
Great explanation of SMPSU's workings.
I've made a good living repairing these mythical beasts in the 80's & 90's, mainly because I was the only one in our team daft enough to work on them live !!
Subbed 👍
This is a work of art! You would have saved lives in EE college
Maybe the best explanations I've ever seen regarding these components and systems. Earned a sub.
Thanks!
I cant word how many times everything just clicked.
such a great video!!
Really excellent! step-by step in easily digestible bits with plenty of visuals and graphics!
This was the best circuit explanation video i've ever seen. Please continue on this theme!! You're criminally under-rated.
This is insanely useful, thanks. I'd love to see more circuits broken down like this.
Perfect I have more planned :)
The circuit he described would break down (well, successfully blow its fuse to isolate) in 1/3000 s. Read an actual GaN FET's manual including the power supply use thing instead. You're welcome.
Please keep it up
Awesome content
Would love to see the switching ps in more detail
Thank you! I'll have a think about which parts are most exciting to delve into
More details please thank you
@@electrarc240the whole thing from start to finish
Just fyi: I recommend DiodeGoneWild videos about SMPS if you want more details.
They do however require a bit more knowledge to fully understand than this truly superb video imo.
I agree with the sentiments expressed in the comments. This was a great explanation. A lot of videos will explain things, but the approach you take is unmatched in my opinion. I'm a 50 year old electrical troubleshooter/technician for a fortune 500 company, my focus is in testing the final products we produce, and the processes are very exacting. So I have a really good understanding of all things electricity, both high and low voltage applications. But I learned from your excellent presentation, and can't give you high enough ratings. Please keep up the good work!
Wow thank you very much!
Thank you for taking the time to explain that SMPSU in such clarity. I have repaired quite a few of these things over the years and have self learned quite a lot about them (including keeping my fingers off the bulk cap!!!). However it is always in my interest to learn and make myself better in my line of duty as an electrical technician.
You are simply a genius. I now understood this phenomenon pretty very well.
Wow thank you very much!
Welcome back 🎉
Yes we'd love to see what make that charger small in size but more efficient
I'll see what I can do!
One of the better explanations of a SMPS that I've seen. Well done!
Thoroughly enjoyed your lesson on SMPS. Thanks a lot for putting up this tutorial for us.
You are very good at explaining, I really liked the real life analogies.
Thank you! I like them too
Good on you! Getting into the garden with buckets and water glasses in your stocking feet! Honorary Cornwallperson!
Love the content, you really have to see all of the power supplies in person to see and feel the difference. Can't wait for the next video!
You really do
Very clear, thorough explanation!
I have noticed how power supplies have shrunk over the years, but had no idea how this was achieved. This video has been a great help. Not least because, to school-level me, a transformer is a trasformer - never heard of an inductor before. Thank you.
I'd heard of an inductor, but never thought that a transformer was one, even though it induces the current from the primary to the secondary. D'oh!
Even though I've been occasionally fixing SMPS's for thirty years, this was very insightful.
Would be nice if you'd address the control loop and bootstrap too in a comparably easy to digest format. If you're tempted to do that then try to find a PSU that doesn't integrate everything in a single tiny chip or find a block diagram for the chip.
🥰Loved this video. I've been waiting for a KA Stroud of switch mode power supplies for ages and here it is. Thank you.
Thanks!
This is my favourite youtube channel now. I really need a break from all the mindless rubbish on youtube which seems to be becoming more of its focus
Brilliant, absolutely brilliant. A really clear and understandable explanation from someone who has prepared well, with a clear delivery and and engaging approach. Thank you I've learned much today.
would like to see some more detailed explanation about how snubber circuit do what they do, especially how it does so without disrupting the rest of the circuit
I'll have a think of a good way to show them in action
@@electrarc240 indeed snubber networks appear to be a black art only few people understand. I've tried sizing RC snubbers in the past, but wasn't really able to find any documentation on them. Felt a bit like trial and error, especially when trying it in a somewhat practical way.
@@j.p.hendrix4389 Yes completely agree, they are very mysterious things
Great explanation and I see what you did there, "annoying EMC regulations". Good one! lol
😁
Love the spring analogy.
Great video buddy, that was a nice explanation.
Could you also do one for how power factor correction works in these power supplies? Thanks
Already in the works! Planning a PCB for it though so could be a while
Thank You :) That was very educational and interesting and entertaining. Nice explanation and good explanation and description of the circuit and functions. Amazing how the density of power supplied have increased over time so much, almost like Moores laws for switching power supplies. Something nice about those old magnetic ones, they last a lot longer, even if less energy efficient.
Moores law is exactly what I thought of! Just need a name for this one 🤔
Simple enough to understand and to the point, well done
At 10:15
Awesome job with the buckets example! I liked how you layered the two.
Beautifully done.
This was a LOVELY and nicely done video. But...please, if I may ask - draw your schematics on some white or light background, not "black on green". It is rather hard to see. I´m speaking for myself, of course, since my eyesight is poor and needs a little more contrast.
Noted! Thank you
FULL BRIDGE RECTIFIER!!!!
Took my full concentration to hold that in when I said it haha!
@@electrarc240 LOL
I love videos like this - I feel like I am in a class.
One of the best explanations I've come across, thank you!
Why miss the control part?
yes, I was hanging on to see what drove the gate on the mosfet...just a timing circuit derived from the smt IC?
Yes, it is also an interesting part, especially how the chip gets its power from the transformer and how this serves as short circuit protection for the secondary.
I decided to leave it out of this video for simplicities sake. I reconned more people would be here for the main power electronics flyback circuit than for control, plus I'm not going to lie control is not my strong suit and I wouldn't have wanted to make any major mistake in my explanation. The control circuit is far more complex to understand in my opinion and I thought introducing things like the tertiary winding may have taken away from the simple overview approach of the video. I will do many future videos on control for example I have a video planned on active power factor correction with boost converter that will delve into PI controllers and more.
I simply clicked on your video as a matter of interest.
I have nothing to do with electronics, but have a natural curiosity about it.
The analogies and filming techniques you used to explain the theories were quite brilliant.
Well done and best wishes with your channel.
2 min 30 seconds in and I can already tell you're a Geniuss👏
Brilliant! Love the use of buckets of water as a metaphor.
J'ai beaucoup apprécié votre description/explication/vulgarisationvulgarisation de d'un typique S.P. . Vous seriez un excellent Professeur.
This is amazing! Very well explained and easy to grasp.
You explained quite well and restrained yourself from using super-technical terms to help those of us who are not schooled in electronics, to understand these very important facts about power supplies. Thank you sir!
For the past few days I've had a little devil whispering to my ear that I don't need to buy a power supply for my project, that I can just build my own. I'm glad I saw this video first.
Be careful with mains!
This is the best explainer I’ve ever seen on SMPS’s, you have a gift for teaching!
Thank you sir, Working principal of SMPS circuit through visual and oral explanation we are really lucky generation to listen 🙏
Where have you been all my life. Great content! Great style, and simple enought for a 55 year old to sincerely understnad. Not a single over the head explaination. Spot on! (needed this education, in case it wasn't clear). Thank you for your time and efforts. THey are greatly appriciated.
Thank you very much!
Great video! I liked your explanation of how to use inductors to do the energy conversion with the spring and the spark - it's so difficult to talk about basic concepts when you learned them long ago, but you did a great job keeping it simple and informative!
Superbly brings out the evolution in power supplies,size reduction plus greater power densities achieved etc.
No, he had one graph that was lovely, but with no particular explanation on what changed.
I'll definitely keep an eye out for more content. 👍👍
In the shortest way possible to describe this video.... Damn good period!
Thank you
The bucket analogy was brilliant!
yes please more videos on smps. Diagnose and repair of common problems. Would like to see a list of common symptoms and their causes and solutions. Great presentation, Thanks
I'm a retired electriconic engineer and think this is an excellent video on SMP supply. Keep up the good work.
I loved the explanation and style of delivery. Well done, you've gained another subscriber today. Thanks for sharing.
..like many of the previous comments on here, thankyou. Youve managed to explain 'those bastard switchmode voodoo psus' as i called them in such a way i finally understand them! Former electronic engineer, now brewer. Thankyou, subbed and liked. Keep the vids coming :)
Great video, explained really well without getting technical. Good job.
By far the BEST explanation out there on a Switch Mode Power Supply.
The only problem I have with these smaller, newer and thus assumed better SMPS is that they are 'noisy' in their output. Maybe okay for charging a battery but not so good for delicate electronics or for LED lighting were some will pickup the flicker off axis.
The absolute best material for smps!! Thank youu so very much for making this video. I loved the intuitive explanations and teaching style!!!
Just want to say thank you very much for the great video you made !!
Congratulations on this brilliant video! I teach electrical engineering and couldn't stop listening for two reasons:
1. Your clear and easily understandable explanations.
2. Your voice and beautiful accent.
I wish I could teach as well as you do!
Ah thank you very much!