Switch mode power supply tutorial: DC-DC buck converters

I explain buck converters (a type of switch mode power supply) and how to build a 5V 5A power supply using an LM2678.
Website: www.afrotechmod...
Parts:
octopart.com/bo...
Schematic:
i.imgur.com/iw...

[@Afrotechmods]

Interested in learning about wireless power? Subscribers can get up to 80% off Wireless Power to the People - Wireless Charging 101 on udemy using the coupon code "KZbin" www.udemy.com/wireless-power-to-the-people-wireless-charging-101/?couponCode=KZbin

[@vsftpd]

I like Afrotechmods narration feels like watching documentaries not lectures :-)

[@democracyforall]

The best person often does not get the best views or hearers. I got an engineering degree but all electrical old stuff not much electronic, your channel is the best of all. Electroboom is good but you are a great teacher.

[@greatscottlab]

Arnold interrupted the best part. Such a buzzkill !

[@Afrotechmods]

Arnold sure loves killing things.

[@mdarifurrahman5674]

honestly I almost fell off laughing when Arnold interrupted...lololol big thumbs up

[@ChristopherJones-ck2zh]

And a suitable slope comp- SHUT UPPPPP! Really Arnold, you are a buzzkill.

[@aheckers]

What...?

[@martinkuliza]

@@aheckers Basically everyone was saying, You're a buzzkill.............STOP BEING A BUZZKILL

[@TexasInstruments]

Great video on how to build a DC/DC switch mode power supply. And, thanks for featuring TI's SIMPLE SWITCHER buck converter.

[@Afrotechmods]

+Texas Instruments Glad you liked it. Been using your products for years!

[@SudarakaMallawaArachchi]

+Texas Instruments I have studied and gone to several lectures on this area, but this 10 minute videos summed it up really nicely :D Kudos +Afrotechmods... keep up the good work :)

[@teadrinkingilluminati9173]

+Texas Instruments i didnt expect that...

[@scotthow2933]

I wished Ti would have more reference designs for us newbies on their chips. I mean more reference on variable outputs using digital pots and linear pots would be nice. More references on pass power transistors for more current output too. I always throw together a lm317 circuit for 15 amps or more to test audio amplifiers. I could figure this out but would rather not blow out $200 worth of parts before I get close. And as far as I can see, none of their simple switchers, high amp series chips have any reference for soft start circuits. What's the first thing a newbie going to build? A high amp variable voltage power supply . Make it easier for them and get them hooked on your products and they'll use them for life at what ever company they're working for....

[@EETechs]

It's sad that none of you guys will do a tutorial video on how to solve feedback loops for compensation networks in switch mode power supplies. You guys always take the easy way out with using devices that have the compensation networks in place. Is it really that hard for people to understand it or is the math too advance that you might scare away people?

[@DIYPerks]

Great stuff! I'm learning a lot from your videos. Keep up the excellent work! Loved how you broke it up with occasional jokes, hehe.

[@filenotfound__3871]

Not expected to see you here :D

[@LightmingGamer]

Oooo u r real ....

[@Shroommduke]

NOW I get it! sorta. Where can I get a "crack-head mashing a mechanical switch" and what's it's service life?

[@jorgewashington2981]

In my neighborhood. They are everywhere and pretty cheap.

[@Shroommduke]

Yea but how long do they last and how reliable are they, and will i have to hide my valuables

[@jorgewashington2981]

Yup. They'll pawn your Fluke multimeter for $20.

[@Shroommduke]

LOL Crack-heads, real life zombies!

[@jorgewashington2981]

Lmao!

[@sanferrera]

Just when I started to get very, very nervous, Arnold came and saved me.

[@jhubertful]

lol same

[@teadrinkingilluminati9173]

yeah, like you got that 69W on accident..

[@AppliedScience]

Good stuff!

[@Afrotechmods]

Omg thank you!! That means so much to me coming from you!

[@AppliedScience]

Afrotechmods Thanks! It's great to see you back on youtube.

[@fohdeesha]

my two favorite utuebs in one place. circle of smarts

[@RimstarOrg]

Nicely done! I like that you also give explanations for why each component is there. Thanks for these.

[@rioschad3284]

"in the real world, this is garbage" - said every design engineer.

[@fingloidfing3337]

i really laughed at that one.. when ardnold said Shut Up! hahahah

[@miguellorenzo3726]

I already saw this video weeks ago. Came back for the arnold scene. rofl

[@Afrotechmods]

You'll be back.

[@kshitijanand163]

You have won the internet for today. Both with the awesome video and the superb referencing comment.

[@phazeman2022]

LOVE IT!!! Too many 'informational" videos that talk about how their cousin taught them when they were 5, how how their dog needs to go for a walk....For an hour. You stay on topic. Thanks. Subscribe.....

[@Leonelf0]

Can you make a tutorial on making a SMPS using a crackhead mashing a mechanical switch?

[@Afrotechmods]

Got a crackhead I can borrow?

[@Leonelf0]

Afrotechmods in my class i have two of them. I wonder how I can send them to you. The german mail will check for human contents :(

[@power-max]

just build the 3:21 circuit and use a big button, a large inductor with iron core (like the primary of an ignition coil), and a huge electrolytic motor starting capacitor!

[@ExtantFrodo2]

***** Due to the high cost of supporting a crackhead, you should opt to use a variable speed motor to mash and unmash the button. In addition to being less costly it would be much more reliable as well. (plus you don't have to remain present to assure it doesn't run off with your expensive silverware).

[@magaphoto]

Since efficiency is the most important part of the topic, I think you need Tucker the methhead instead of a crackhead. kzbin.info/www/bejne/o5eWlmR8ZsZjfsk

[@RossPotts]

1:12 - "or even a crackhead mashing..." I love the humor this guy puts in his videos!

[@rl9296]

My name is buck and im here to convert DC

[@dtm876]

There are some pretty expensive books and people with extensive credentials that can't explain this as simple as you have. Thank you. :)

[@minkorrh]

It's good that these videos are available and teaching people. I really appreciate the time it takes for yourself and other engineers like Dave at EEV blog, Mr Carlson, Great Scott, and everyone else creating these videos explaining electronic theory.

[@Afrotechmods]

Glad you like them!

[@Blaff3tuur]

Nice to see an EEVblog reference

[@Afrotechmods]

Dave is badass.

[@iDomoPolyForums]

Afrotechmods He's been getting a bit too much into video blogging instead of electronics lately. :(

[@DavidLindes]

Afrotechmods in the future, could you also include a link in the description? Then I could see it without needing annotations to be on (or on platforms that don't support them!).

[@easyamp123]

good video, simple switchers are not cheap though. what's the maximum switching speed if I use crackheads?

[@Afrotechmods]

+Thad ward Around 100kHz/gram.

[@jorgewashington2981]

+Afrotechmods lmao per "gram"

[@KostadinIVKostadinov]

Dave is everyones idol :D

[@mcboomsauce7922]

i actually laughed my ass off....thank you

[@-na-nomad6247]

after the "shut up" I paused the video because I kept laughing and couldn't follow XD (still laughing by the way)

[@rouuuk]

btw are still laughing?

[@317andrew317]

LOL I literally had my mouse on the back button as soon as Arnold came on, impeccable timing. That was the most hilarious moment of my week, thank you! Your videos are fantastic! 4:06

[@4dirt2racer0]

haaaahahaha "or even a crackhead mashing a mechanical switch" i was NOT expecting u to say somethin like that, awesome man it helps break up that monotone feel

[@williamking9707]

"Practically idiot proof" Project Farm: "We're gonna test that!"

[@ylstorage7085]

For those who wants to know the rest of the components interrupted by Arnold @4:07 A droid motivator and a Hyperdrive.

[@hitandrepair]

Say you have 12-30 input and wanting a steady 24v, current draw on 24v is never higher than 0.8 amps, how would you calculate what size fuse you need on the input side of 12-30v?

[@Mushketer888]

I was experimenting with 555 step down/step up all you need is mosfet/npn for step-up or pnp/p-mosfet for step down and zener diode+transistor so you pull down reset pin on 555 with transistor (which is pulled up with 10k) voila, you have voltage stabilization maybe tl431 also will work like this if you like my idea

[@SUPERTROYANO666]

Hola soy de México, y me gusta tu canal, aunque aun estoy aprendiendo hablar ingles, aveces tus videos se explican solos con la imagen jeje, saludos y Exito!!!

[@JAKOB1977]

4:06 perfect timing, at least according to my brain in trying to comprihent it all.

[@pipe79000]

Hi, If i have a 500 V generator and 60Hz , what type of switch mode do you recommend to me? Do you know about some company with this type of products?

[@corlfranco9371]

a variac or a bt151 /bta 08

[@wmd5645]

Not a EE guy... When I hear large capacitor and see uF my brain is like wtf. Is ”large” relative to the V/I of the given system? bc I’ve even heard .1uF filter cap is considered large in a guitar pedal application.

[@unamename1075]

Good tutorial. One question: Can i make a variable buck converter to change output from 5v to 4.2v or less. Can i change output by just changing the frequency at switch Mosfet

[@DigBipper188]

you shoulda called this video: "How to build an 80+ silver power supply" that's a damn efficient little converter!

[@ronaldlogan3525]

where can I get a crack head ? Does Digikey stock them ?

[@Surajkumar0770]

Shut up.. Hahahahahahahah

[@anjunzhouJack]

Hi man. Very nice videos with parts attached. Question: Why do you need two caps in both input and output? Can you just use, say, a big 300uF in the input? and 10uF is nothing compared with 1000uF in the output. Why do you need two? thanks a lot

[@MyShowtime33]

LMAO!!! the arnold quote "I lied" made me laugh hard for ten minutes.....awesome....great video...i appreciate your works...

[@typingcat]

Remember when I said I hadn't lied? I lied.

[@PCSolutions94]

Great tutorial! I'm currently trying to debug a couple of server smps's. Very complicated technology, seems like many components are prone to failure. Your explanation was very helpful. Keep it up!

[@Yahweh_Is_Great]

man i can't stress enough how helpful this was, i've been looking into buck converters for awhile now to step down a solar panel and increase my current to a demanding load. I was on the verge of making my own converter with a self-programmed controller b/c i couldn't find an IC on mouser lol your explanation and guidance to TI's simple switcher saved me a LOT of time...Thank you

[@edgars007]

Although I know what you are talking about, I still want to see all your videos from beginning till the end! Great teaching man! I think Arnold is proud of you

[@power-max]

"and a suitable slope compensat----SHHHUUTTT" Hey AfroTechMods, what were you going to say? I was following along perfectly! 👌 I actually built that "hard" circuit with an LM339, it worked like absolute shit LOL! Due to parasitic oscilliation on top of the switching noise. So more details about this compansation device?b

[@pawwel1990]

Arnold shouting "Shut Up" made my day and bought my heart. Subscribe :D

[@Leonelf0]

Are you using two types of capacitors for decoupling so you can cover more frequencies?

[@Afrotechmods]

Yes. And also it lowers the total ESR, reducing input and output ripple.

[@John_Smile]

Could you build a Buck/Boost Converter with current adjustment, not just voltage ajust? Also, I would like an output current greater than 1 A. Maybe 3-5 A would be OK. I saw some clips using CI 555.

[@DantalionNl]

I see you got a better oscilloscope agilent very nice! may I ask which model you have ?

[@damiendivittorio6973]

Love your videos man! When you started in on the feedback loop I thought my head was gonna explode! thanks for the alternative. I want to understand all that someday...

[@Palmit_]

1:10 or even a crackhead mashing a mechanical switch .. 😂😂😂 omg.. my sides 😂😂😂

[@power-max]

I have actually made some simple buck converters using an NE555 and some op amps and comparators, they do not work well though, (MOSFET heats up too much and has poor regulation)

[@ElectronFunCom]

This video is great! Because of you I started experimenting with buck converters. I found out that buying individual parts to build your own buck converter may be more expensive than buying an assembled device. I don't mean wholesale quantities, just 2-3 items for my projects.

[@sghost128]

Can I find "crackhead-mechanical switches" on Mouser?

[@Ivo--]

Ha ha you said doodie.

[@LTJR.]

1:16 Efficiency be damned -in the name of humor let's try that crackhead...WAIT... It's a win-win they'll work for rocks! HaChaCha!

[@EdwinFairchild]

Dam I would have love to learn how to really build one as oppose to the plug and play option. For the sake of learning !

[@SciHeartJourney]

The LMZ3 series parts are 0 stock in the US until next year The $8 part I'm looking for cost $800 at most places. I was lucky to get a few for $99 each. 😖 So I'm building my OWN supply. That's the reason why I'm even watching these videos.

[@WinstonSmith1984]

What are common switching frequencies of buck converter chips? I've noticed that many switching regulators produce radio interference on 433Mhz (RC), which is quite annoying.

[@Afrotechmods]

Anywhere from 40kHz to 4MHz, and it keeps getting higher as technologies improve. Switching frequency definitely affects the amount of interference put out, but good PCB layout and good component selection make the biggest difference. Learning how to design a good SMPS is almost an art form and I barely scratched the surface with this video.

[@jordananderson3665]

SHUT UUUUUUUUUUUPP! omg i lost it lol

[@thorlancaster5641]

A LM317 doesn't usually smoke like that. It has thermal overload protection. Anyways, great video.

[@dinaabdelki568]

Mate ur great n everything just Please don't do the Arnold thing again please.... You startled the hell out of my brain circuits....!

[@AdminTechnopedia]

lol :)

[@ziadfawzi]

Thank you. The video was very useful and simple.

[@knachoo]

If I understand correctly, it draws less current while providing 2A output current (Shown in efficiency calculations). That means, I can use a 12V 2A (24W) common adapter to power 5V 2A (10W) Orange Pi and and 12V 500mA (6W) white LED strip. Correct me if I am wrong.

[@muhammadbilal2000]

Thank God, Arnold appeared and said shut up, otherwise I was going to stop the video hahaha. Kidding, great stuff like always. Thanks a lot :)

[@1miltond]

Hi you have any videos on step up ideas less say 12VDC input 35 VDC output 20A is this posible ?

[@Alex1M6]

Nice job getting the LM267x series to work well on perfboard! Without using snubber networks I could only ever get them to give low output ripple by using a PCB with ground plane lol.

[@Afrotechmods]

I was pretty impressed that I pulled it off on perfboard too! The huge ceramic caps I used were larger than you would ever need in a commercial design, but they give extra leeway for beginners to make mistakes and still have good performance.

[@ihatenumberinemail]

Afrotechmods Will the efficiency be higher if I solder the components directly to each other?

[@marcodev3375]

Can buck converter increase the output current? I want to convert 12V 2.7 A to 1.5 V 20 A. I was built one using push pull oscillator with transformer (fewer turns on secondary), but produces hundreds KHz AC output that I must handle with skin effect. The AC output cannot be converted to DC easily by using reflecter diode, small resistance will produce loss / heat because low voltage high current.

[@maxk4324]

I'm having some trouble with my circuit. I need to switch some large currents and I'm using a TO-220 crackhead, but do you think the TO-3P package would have been a better choice? What kind style crackhead do you normally go for?

[@jakeleno7180]

@Afrotechmods, What would be the advantage of building this (besides knowledge & personal satisfaction) over just buying one off Amazon? I see the cost of parts from the link you give in the description is around $12 while I can purchase a buck converter off Amazon for $6-7

[@PreludeSon]

Hahaha...."shut up...." Would you mind making a video about ARM processor GPIOs and it's characteristics?

[@samhitech]

+Afrotechmods I'm working on a 5 volt power supply to charge a smart phone from a 12v lead acid battery I was using 7805 regulators but they gave me low current then I tried lm317 but it was worst than i imagined so my question is : Is it safe to use buck converters to convert the 12volts of a bettery to a 5 volts with 2amp at max current or what protection can i add? please help me?

[@MommaBao]

"crack head mashing a mechanical switch" ... LOL

[@Elfnetdesigns]

It's the same circuit they put in vehicle chargers for smartphones. 12V in 5V out

[@fritt_wastaken]

Why is there 5V on the output without a load? Whats preventing it to bump the voltage up to 10V? Also my LTSpice simulation sometimes just goes crazy with this circuit. I did something wrong?

[@spitti3]

Do you have any experience from Picoscopes? I was thinking of getting their entry model 2200A, and use it with my laptop for hobby projects, it's tempting since I could get the scope and two voltage + 1 current probe for less than an entry level bench scope alone.

[@BlackWolf42-]

Can anybody recommend a way to keep the noise this type of power supply creates from interfering with other electronic devices attached to it's input and output? I use a Buck converter type DC-DC converter in my RC airplanes for LED lighting.

[@michaelstora70]

What is the best way to add a current limiter to a buck converter (CVCC)? Say 5v from open circuit thought 1.5A and then maintaining 1.5A as the load increases.

[@BEDINSSGUKRAINE]

Hey people, i need a circuit with following property: 400 DC to 12 Dc mac current output up to 150mA. Which parts do i need to. This circuit will be connected to capacitor.

[@Spannertech728]

Hello Mr Afrotechmods - I've watched a few of your videos and am so impressed I wanted to add you to my list of poeple I give to on Patreon, but Patreon doesn't find you. Are you called something else there? Thx OP

[@richardlalaz6020]

Great little video. I wonder if anyone can help me. I'm looking to build a 12v and a 5V power regulator with NO ripple. It should be easy to do as input is 12-14vdc with lots of noise on line.

[@iamdatdude1619]

LMbao this is why i love your vids you break it down simple! just like a Crack head mashing a SWITCH LOLOLOL

[@danielugwa6517]

thank you sir I appreciate God bless. sir please can you help me on how I can achieve 12v volt of DC DC booster and get the out voltage of 24 to 32 volt with amp rate of 60 or more than please thank you

[@nassermallah7098]

Good video.. I have a question.. Can a buck converter charge on a CAPACITIVE LOAD?

[@Afrotechmods]

Sure but it might end up being current limited if it's a really large capacitor.

[@MrFelixkkw]

Hi, i am building the same circuit as I powered the input side with 12v lead Battery but it is very hard to turn on. When I measure the input to ground I only get 3v feel like smtg is blocking the Voltage going in bcs this IC needs at least 8V to turn on. I check all the connection and parameters. I am sure the circuit is correct as it manage to turn on and drive some leds before but it turn on quite randomly after leaving it untouched for random hours. Any idea why ?? Thanks..

[@gerrys6265]

Great videos generally, thanks. BUT talking way to fast to follow if one is at a level that you need this tutorial at all. Don't forget it is a tutorial and you are therefore not talking to people who have a full grasp of this stuff - or you wouldn't need the tutorial.What confuses me most is the capacitors....there is never anything that tells us shy we need a specific type (or combination) of capacitor types for a specific job... Cheers

[@akroutsamo]

Hi , thanks for the explanation on the buck converter , but let us just say we want to build a 12v to 5v 20A smps , I'm sure that this type of converter can't respond to our need especially it is not isolated , a flyback converter is one of the choices but the construction of the transformer wingdings is a bit challenging ! can you make a tuto about this topic and how hard can it be ?!

[@percivul1786]

Noob question here. How do you calculate the inductance you need to accommodate certain amp requirements. If I wanted to make a buck converter that could handle say about 5v at 10A, what is the method to calculating the inductor in that specific example? Is there a calculator or website that would do that? I haven't found one quite yet.

[@Dentinvent]

very well made video thanks. Nice burning components shots too.

[@saadjahakayani5020]

well explained ,i am looking for circuit which can light up my 12volt 1amp LED from main 230 volt to 12 can u help me in making switching mode power supply

[@fmassaretto]

Can I use this circuit to power a Raspberry Pi, for example? I mean I know that RPI 3 is 2.5 A so more than enough but there is anything that I need to worry about , maybe the ripple?

[@grahamhall2662]

Excellent thank you. I have such buck converters for use in rc radio control but am doubtful as to their reliability due to noise. How can I reduce the noise created? Regards.

[@m3n4lyf]

Ok, but what if I actually didn't want you to shut up? Where is that video(webpage, pdf, online course...)?

[@koladeshodunke1543]

At 4:04 can you explain further how to implement the closed loop circuit in a program like PLECS. What is the Vref and how is it controlled?

[@aidanfranits1339]

What kind of MOSFET would you recommend for a buck converter circuit? N-channel or P-channel?

[@sushmitadanuwar8542]

Better then greatscott

[@Dragonmastur24]

Thumbs up! I was thinking though that any power conversion that uses a coil to store energy(not for filtering) is technically an inverter? is this correct or no? thanks though for a great vid, and for burning up your circuits in the beginning xD

[@uiticus]

Isn't adding the 10uF ceramic capacitor in parallel to the 1000uF electrolytic capacitor redundant since they are in parallel? What is the purpose of adding the 10uF capacitor?

[@entemomohTV]

Now, I know that this is sort of a dumb question, but what if you used a microcontroller with meassuring guages or so, to regulate the duty cycle? I mean you would have to meassure current draw or voltage de-increase, so that the microcontroller can regulate it right? just tell me if I'm dumb

[@mohammedzaman1937]

nice video. i have a SMPS that can give 12 volts at 60 amps. i want to make a circuit that can convert it to 5 volt 100 amps. is it possible? can you give me some idea. thanks in advance.also can i use couple your circuits in parallel to achieve higher current?

[@322doug]

thanks man, i just built it, and it is great, thanks again!!!