Probably the most used component nobody knows of! TL431 Guide! EB#50

[@greatscottlab]

The first 1,000 people to use this link will get a 1 month free trial of Skillshare: skl.sh/greatscott10211

[@mateushff1445]

T I M E T R A V E L

[@nathanielluke2084]

1 week ago pog

[@thekaiser4333]

What is this skillshare-pest on youtube?

[@hrbakery2]

Too Late

[@misterhat5823]

Thumbs down for skillshare,

[@jensschroder8214]

I had a 24 volt switched-mode power supply but needed 19 volts. To do this, I simply changed the voltage divider on the TL431. I connected a potentiometer (value corresponding to the old resistor that I removed) between the plus 24 volts and the 2.5 volt sense point of the TL431 and reduced the value until I could measure 19 volts at the output. Then I replaced it with a fixed resistor.

[@salihay]

Is your power supply still working well now?

[@Jackson22379]

@@salihay sorry he dead, May his soul rest in peace

[@38911bytefree]

It depends on the design, some controllers will have undevoltage protection on the VCC pin that feed them from a separate winding on the primary. Lowering the voltage of the output will lower VCC too. Doing the other way (try to change the voltage up) can also fail because the same issue. Some PSUs are pretty basic and will not care. Other have this protections and zeners as double safety, usually triggering from a dedicated optocoupler in case that everything fails (laptop chargers). also note that 817-alike opto polarization changes and its components need to be upgraded. Rising the voltage even when it looks "FINE" is not advisable. This PSUs have nothing to spare. Spikes when swithing off will kill the mosfet or reverse voltage will exceed the rated of the ouput diode. Otherwise ATX psus will make a great labo PSU ...and they are NOT. Tweaking an ATX PSU to ouput a higher voltage is a recipe for disaster.

[@sofiaco1513]

TechBuilder made a short facebook post on this a few months ago. Never knew how nifty it could be by adding an outboard pass transistor. Been using it as a handy adjustable voltage reference for adcs

[@greatscottlab]

There are truly many applications :-)

[@mysock351C]

I'd have to dig it up, but there was even a switching buck regulator example in one of my old Motorola IC catalogs that used a linear regulator as the sole control in the circuit. Not sure how accurate it was, but it was impressive to see someone using a linear circuit to do switching regulation. Really are lots of applications for something you would not think of.

[@LeonMatthews]

This video combines my two favourite things! A deep dive into a fun component and its applications, and a component that has become cheap because of how often it is used in industry. My last project actually used a TL431 - a voltage monitor to automatically cut-off power from a lead-acid battery for only a buck or two in parts. Thank you, and keep up the great videos!

[@greatscottlab]

Thanks for the feedback👍 Glad you enjoyed the video👌

[@rhr-p7w]

Hey Leon, do you have an scrhamtic for that? I'm trying to build exactly that, but most cut-off circuits I found are op-amp based (just the ones I don't have on my parts bin)

[@LeonMatthews]

@@rhr-p7w Of course! I'll draw it up for you tonight (NZ time). Prepare to be underwhelmed though... Conceptually it's the same is the circuit Scott shows at 6:50 - but with positive feedback to turn the MOSFET hard-on to prevent overheating (also oscillation), and inverted to use a more efficient (and cheaper) N-channel MOSFET.

[@sauritinfo2248]

As new electronics thinker, I was going to order a whole kit of zener diode ....but after watching this video.....I will just buy some of these TL431. This is really good to know about this. Thank you #greatscott

[@kennmossman8701]

Yes but............you do have the limitations of the TL431. A Zener can be a simpler, cheaper solution with lower parts count.

[@Frankey2310]

Strange - I use TL431 all the time. One of the best ways I found to control the current of a high-power LED (either linearly or through a switching converter) is with an op-amp comparing shunt voltage to a reference. TL431 is the exact thing you need for the job - the 2.495V it produces by default can be easily divided into anything you need, and, unlike a Zener diode, it can sink a wide range of currents with Vref staying within a tight range. It's basically an extremely accurate Zener that doesn't require you to meticulously precalculate the value of R_Z. Simply great!

[@TiredOldDad1]

I am an electronic repair technician and I work on many types of switch mode power supplies. The TL431 can fail sometimes and it is difficult to diagnose because it does not short or open like a defective diode would. It will measure identical to a known good one using a multimeter or a curve tracer. In some cases the only way to know is to replace it. The symptom is usually a pulsing output where the DC is jumping past the rated voltage output. There are other things that can cause this symptom too, making for a difficult diagnosis. Your video was extremely good. Thank you!

[@ELECTRONOOBS]

What a huge coincidence to have the same topic. When I've posted my video and saw your post too I couldn't believe it. The odds are low:))) Btw, very nice video 👌🏻

[@greatscottlab]

Well, not such a big coincidence. I published the video about 2 weeks ago on Patreon and since you are a supporter I thought you saw that. But its nice to have more than one video on the topic👍 This way we can cover all the details.

[@ELECTRONOOBS]

@@greatscottlab Exactly, is still a coincidence for me. You posted on 22nd and I on 23rd 😱 This universe ... 🤣

[@RMquickbit]

This made me laugh. No disrespect to anyone but it was obvious when you posted this 2 weeks ago then a video come out instantly on this exact ic via electronoobs it doesn’t take much analysis to see what happened here. Good on you for noticing the same.

[@RMquickbit]

Also you posted a teaser picture even before that….

[@anonuser2640]

Both of you has to many coincidences 😂

[@piconano]

Please keep in mind one important characteristic of this programmable Zener IC. It's fully temperature compensated, unlike any Zener that ever lived. Zeners are so yesterday.

[@arthurmoore9488]

It's really insane how much voltage drift things like temperature can cause. Of course, that's what happens when you amplify errors. Going from a 24V signal down to a 5V for ADC measurements doesn't sound so bad. Until you realize that the max needs to be closer to 30, so any errors are magnified 6x. At that level, even small differences become a pain to deal with.

[@jmi5969]

"Ever lived" is an overstatement. There is a whole class of temperature-compensated zeners, like the 1N82x series. The genuine 1N829 costs about two hundred times more than noname Chinese TL431s, but it has a rated tempco of 0.0005%/K. That's 0.05% change over a 100K interval, far better than even the best-grade genuine TL431s. And if the app needs the lowest possible noise, again, the zeners are naturally quieter.

[@DrakeOola]

@@jmi5969 Get learnt.

[@klave8511]

Zeners are here to stay for safety. Approvals agencies recognize it behaviour in a protection role, an ic can’t replace a zener here, they’re too slow and failure mode is not consistent. Zeners are cheap and available in different power handling sizes. Massive current pulse handling capability.

[@georgeh1352]

Working out how circuits work doesn't come easy for this old guy, so good explanations are a God send. Many thanks, have subscribed and hope to see more of your videos.

[@PlaywithJunk]

I recently used the TL431 for balancing supercaps. Acts like a 2.5V Zener diode without any additional components, just REF to Cathode.

[@waqaszahid86]

A very useful component, discovered it not too long ago when I tried building my first switched mode power supply, since it is so cheap and easy to get I use it in all sorts of applications from voltage references for arduino to tiny constant current load for my power supplies, amazing how versatile this little component is.

[@mikemike7001]

The TL431 has been used for decades. Introduced by TI in 1977, now made by many major semiconductor companies.

[@d614gakadoug9]

Yup. Anyone who has been in electronics for very long should know about it. A "precision" programmable reference it ain't, but it's not too shabby and it's useful for lots of things.

[@scunnerdarkly4929]

This is the freakiest thing ever. Possibly. I’ve literally just been pricing up TL431s for the SMPS section of the Mac Classic analogue board (PSU and CRT section) schematic I’m staring at right now, when the notification for this video came through. Timing could not have been more perfect!

[@greatscottlab]

Haha I hope my video helps a bit ;-)

[@mmghv]

How about when I first stumbled upon it when trying to fix a charger, I fell in love with it and started tinkering and hacking with it, only to start finding my favorite youtubers one after another making a video about it.

[@derrekvanee4567]

And a fww days ago. The otjer big maker did a 43q video too what a. Treat as I've been learning vrefs lately also

[@bobweiram6321]

It's called KZbin Serendipity! Sometimes I will see two or more videos covering the same general topic on the same day even though the topic isn't news and the content creators don't know each other. I've also had cases where I was struggling with an issue and lo and behold, the solution shows up on my feed minutes later! It makes you wonder how random the universe really is.

[@joop2295]

Used the TL431 in several applications,. Yes, very versatile component! You call the internals of the TL431 a comparator, but it is really an opamp. You can use an opamp as a comparator, but in most cases you cannot use a comparator as an opamp, because comparators are not stable in the linear region. A TL431 can be used in the linear region, when you use proper compensation.

[@jeffm2787]

TL431, I've got hundreds of these I've pulled from SMP's for years. Great little part. I've watched some over time on my 3457A and they don't drift all that much, pretty good for what they are normally used for.

[@keithking1985]

WOW! Can't beileve you never worked with the TL431 before.. it's everywhere! It will become one of your favourite IC's.

[@sundog486]

Yes! Have used them for many years.

[@ripleyleuzarder630]

My fav Op Amp was the 741, and was in a class with its designer as our instructor in 84. I like the way you present your evaluations Thanks

[@uecmitsuimarinedieselengin873]

What a useful nice video ! i come across videos about SMPS in China everyday but i didnt know how TL431 functions. You have solved my questions, thanks.

[@NiHaoMike64]

There was a contest around the TL431 a long time ago, the winning entry was an audio amplifier for a crystal radio. Looks just like a transistor, the volume from what appears to be a crystal radio augmented with a single transistor amplifier was just incredible.

[@GogiRegion]

It’s incredible how much can fit into so little nowadays. We’ve basically gotten some components down to the point it’s able to be easily measured in atoms wide, like transistors with their less than 100 silicon atom wide. It’s crazy to think that we’re approaching the atomic level for how small some electronic components have been.

[@Raz82000]

It's an mk484 i guess.

[@TheDarkKl342]

I mainly use it for battery discharge indication on pretty much all of my battery-powered things. There is a simple circuit with 4 resistors, TL431, 1 NPN transistor and an LED that lights up when the input voltage drops below a threshold set by the resistors, telling you to stop using the thing and charge it. The warning threshold is set by the ratio between resistors and can be adjusted for use with various amounts of NiMH or Li-ion batteries in series. For example, having a 3/10 ratio (10K/33K) makes the warning LED light up at about 3.3-3.35V, or 3/1 (33k/10k) for 3S Li-ion and 10.7 V (3.5 per cell) warning. When this is added as a module it draws very little power when idle, so i recommend everyone to try it

[@DrZipZwan]

Thx very much, do you have some tuto on how to build the circuit, and information about how to tweak it according to each use??

[@CircuitShorts]

Just recently I was looking up the internet for over current pull down protection for my circuit and this IC popped up... Thanks for explaining the working in details!

[@br1ckbr3ak3r]

Anyone else on youtube: Let's get started! Great Scott music starts playing in head

[@memejeff]

It's incredible how such a small component can be so useful. Amazing vid as always. Gonna buy myself some TL431's.

[@TheMainsheet]

The problem with most switch mode power supplies is that of Radio Frequency hash they produce that wreaks havoc with radio communications devices. These units can be filtered, however, that is an added expense that most manufacturers ignore and therefore dont implement.

[@BobMonsen]

Think of the TL431 as an NPN transistor with a Vbe of 2.5 volts, and a super high beta.

[@greatscottlab]

Nice comparison👍

[@martinvollderpro]

@AlHasan Sameh gain

[@freakbot1056]

I don't know what you mean ,but guessing it's pretty rad .

[@jmi5969]

@AlHasan Sameh There is no beta because there is no current-to-current multiplication; input current does not change much at all. The TL431 is an "almost true" differential voltage-to-current converter. Once it had reached the on-state threshold, it converts 1mV input (referenced to the threshold voltage) to 1mA of output current. And the maximal voltage gain is around 1000 or less (compared to around 3000-6000 for a silicon BJT).

[@ferrumignis]

It's more like a three pin op-amp with a high but very stable input offset voltage.

[@NickElectronics]

Great video! I found TL431 2 yeas ago, and from that time use it in almost every circuit when i need to get precise Voltage Reference)

[@marka1986]

One thing I haven't seen addressed....unless I missed it is that when you use this as a zener, the feedback resistors have to be quite a bit higher in value than the current limiting resistor.

[@Flip-Flop-Rio]

Scott, good afternoon! Really the TL431 is fantastic. When I discovered it about 2 years ago, I was also surprised by its accuracy for a very small price. I set up a small 5v voltage reference to calibrate small 3 1/2 digit multimeters. I'm from Rio de Janeiro - Brazil

[@ucantSQ]

Good find! And even better that you felt it was cool enough to feature in a video.

[@cavemandanwilder5597]

I have a TL431 acting as a voltage reference in a few low-voltage-battery-cutoff circuits. I like to replace alkaline batteries in the cat toys we use a lot with lithium batteries, and I add a cutoff circuit to make sure the battery doesn’t discharge too far. Only five components! EDIT: No joke, I wrote this before the exact same circuit appeared in the video @6:50…..GreatScott is always two steps ahead of me….😅

[@greatscottlab]

I just knew it😉

[@omsingharjit]

0:52 Never worked with it B4 !! Surprising ........!

[@Mohammad-_Asad_Haider]

10 days or so I was looking for the same ic on youtube to find a detailed video about it...what a coincidence that you chosse the same topic for your video. Edit:Thanks man

[@greatscottlab]

You are welcome👍

[@M0XYM]

Regarding SMPS's - these often have EMC issues that designers overlook. Such issues can plague and pollute the radio frequency environment unless the designer has taken great care. I wondered if you could do a series of videos on these EMC issues?

[@electronichaircut8801]

He already made one.

[@user2C47]

And apparently some designers don't care at all. I have a Chinese power supply so bad that it can light an LED with just the noise. (Not even a complete circuit!)

[@nicholasroos3627]

​@@user2C47 If you don't have bearing on what countries EMC requirements you need to meet in which part of the world then, yes, it is a rather dubious task. I completely agree.....massive vent holes and poorly bonded gaps in chassis of most SMPS and the fact that a good number of current product designers aren't instructed on giving a shit to begin with does not help the situation. IE not a China issue.

[@KeritechElectronics]

A nice and pleasant introduction to SMPS design, construction and modding. Thanks a lot :)

[@synqelectric6163]

Great Scott. If only you knew how much influence you had on me since i started watching your videos. Actually, i improved my veroboard skills by seeing how yo neatly arrange components in yours. You are my mentor. Thank you so much. 🙏🙏🙏

[@Den_Electro]

Hello Friend! Watch my video! kzbin.info/www/bejne/iISti32Or8yNh9E

[@stevedaenginerd]

Thank you for putting these EB videos together and sharing them! I really enjoy the "bite sized" info you give on a subject. You don't go into super detail, but give enough detail so that we can go off and find more details! I would love to hear your take on a deep dive into feedback theory and design. There is some much more to this subject that is not really common knowledge, so to speak. Ya know, I don't know what I don't know. 🤓

[@tobias7166]

GreatScott: Switch mode power supply are amazing ! Measurement Engineer : *screaming*

[@antonycasanova4067]

Wow, Das ist eine nützliche Komponente, danke!

[@Geniusinventor]

Wow man . It's a very good king ic I will make a low voltage cutoff safety for my diy battery bank . I love it

[@greatscottlab]

Great 👍

[@Geniusinventor]

🙌🙌

[@ahmedansari6827]

Oh my god!!!!! This is awesome!!!!!!!! Your videos are a little fast for me, unless I already know little bit about the topic. Is that a flaw? Not at all! For details datasheets are always there, But these videos show us a picture of the universe, what all things are possible and what IC/component to look for the job! Ofc can expect to see each and every planet in an image of the universe! Keep it up bro!

[@robinsattahip2376]

Thank you, I've found these things in 50 cent phone chargers I've bought solely for experimentation and dissection. Never quite knew that they were but assumed it was a switching transistor. (my fault for not doing more research) PS No, I would not trust or use one of those cheap chargers but they're fun to mess with.

[@sysghost]

Thanks

[@greatscottlab]

Thanks for the support :-)

[@electroinduction1512]

Ahhh yes voltage reference tl431 one of the most usefull components. As always awesome video🔥🔥🔥 Cheers!

[@alexoja2918]

I've been looking for sharp zeners for my projects for ages. This thing with a transistor will suffice. Thank you!

[@unbekannternutzer8506]

9:27 wasnt the vce of the npn around 2.0v as mentioned before in the Video?

[@aayushpoudel2362]

Electronoobs made this video 1 week before anyway both of you explained it beautifully.

[@greatscottlab]

I published mine 2 weeks ago on Patreon😅

[@peterwan816]

i also love high-efficiency power supply, that is why I was planning to transit to GaN power supplies. however, there were too expensive to purchase a reputable brand's GaN supplies, at the end, I have to set it aside to wait for the deduction of price for GaN power supplies.

[@smartgamersify]

The best video I've ever seen on KZbin for feedback cantrol system on KZbin.... Sir also teach us feedback oscillation theory... Damped, under-damped and over damped systems

[@greatscottlab]

Puuuuhhh that is quite a lot😅

[@harshgandhi100]

Awesome, TL431 is a real versatile component. Great Video.

[@greatscottlab]

Thanks!

[@martinadini4142]

the thumbnail reminds me of JEVIL , one can only hope

[@Jasmarkelina]

Martina?! Are you trying to learn about electronics aswell?!

[@missingno2401]

*chaos chaos*

[@carldawson5069]

In the early 80s i worked at company making specialty handhelds. They would transmit feild service data to a receiver which formated and handed the data to a host computer. A salesman cam to sell switching power supply for the receiver. The VP said no thank you because it did not weigh enough. Managers would not pay $5000.00 for the box unless it had the transformer weight. Of course this when some companies listed RAM in bits to compete with computers list RAM in bytes. Now of couse many manifactures and customers are better educated.

[@electroquests]

You should make a video or video series on feedback loop design. I would really appreciate it and I am sure others as well

[@anneallison6402]

Did he ever do it?

[@electroquests]

@@anneallison6402 I really wish

[@RoyalTech_2024]

Very good video mate.

[@apegues]

Excellent printing from a southpaw… our writing/Printing is usually pretty bad, good on ya!

[@jacobwcrosby]

*I AM SO GLAD WITH YOUR FREQUENCY OF VIDEOS LATELY!* I know full well how much work this just be for you, but I think I speak for a great many of us, it really is exciting to see a new release from you! No matter the topic, you make it understandable, entertaining, engaging, and simply watchable for just about anybody. *I think it is your super soothing cadence of speech, and that sweet, sweet German accent!* 😁😁😁👏👏👍🏼👍🏼👍🏼😳😳😃😃😃

[@greatscottlab]

Thanks for the feedback👍 I really appreciated it👍

[@michaelbaur5954]

I use the TL431 since many years for Lithium charging an discharging management.

[@brutester]

You can build an Electronic load with TL431 and a power NPN or MOSFET. I had made 3 of them like 7 years ago. Still working without issues.

[@electronic7979]

Helpful video. I liked it 👏

[@MrGeoffHilton]

Thanks for the info, never realised how important this component is, cheers.

[@jtb8631]

I love the tl431, so many uses

[@stevecann3394]

I'm going to keep watching your videos until I understand them!

[@furqanahmad943]

I was searching about tl431 but could not find any video related to it .Thanks for this video .I want to learn more about the uses of tl431 . Can you make another video about it .Still Thanks for the video really appreciate it.

[@W1RMD]

Thanks! I enjoyed that. You have great info on your channel!

[@gabrielenriquemartinezllan9224]

Simply very excellent video!

[@rhinoreign1324]

Yo Scott. Many thanks for the great tips and detailed explanations you always provide. I thoroughly enjoy watching your videos as the Electronics-bug got me, and your content along with ElectroNoobs... and I'm sure there's many more out there, really helps me ease in to the system without TOO many uncertainties. Safety precautions are at a high as I'm just getting started. Anyway, just thought I'd express my appreciation for the time, effort and energy you've put into your VERY WELL documented & Tested Content! Cheers mate!

[@paulsampson6286]

"But don't worry, I will keep it super simple, and not talk about things like Laplace Transformation." I actually quite like the math! Please consider including it!

[@sarathai2876]

Great video I love videos that explain the basics of a component

[@andrewallen9993]

Another great invention from Hewlett Packard :)

[@PhG1961]

Excellent video, very well explained and also a very usefull/interesting topic !

[@corynrobinson]

Power supply circuits are far from my area of expertise, so this was very informative

[@friddevonfrankenstein]

This is awesome. I hjaven't looked at the datasheet yet but I already have possible applications running through my head like crazy Oo Thank you :)

[@21degrees]

I like the 10-12 minute format of this video and I hope you will revisit crossover designs and high voltage for the eskate board and it will be successful. Cheers!

[@greatscottlab]

Thanks and I will see what I can do :-)

[@andymouse]

About time this little darling got some loving....cheers.

[@greatscottlab]

I gave it my best ;-)

[@MrFring]

More videos like this please. I want to learn more! MORE!

[@sundog486]

@3:02: It is not true that it only operates on 36V. Even the application circuit shows a 19.1V supply.

[@hugobloemers4425]

I am thinking more in terms of using it to bias a vacuum tube. Very cool component.

[@JawadAhmadsahibzada]

Now this is the interesting topic , will watch later with coffee 👍🏼👍🏼👍🏼 Great 👍🏼Scott !!

[@greatscottlab]

Hope you enjoy!

[@rashidak7821]

Good video bro 👍 I am from Kerala India 🙏

[@greatscottlab]

Thanks and welcome

[@tafsirnahian669]

Never clicked a video so fast :)

[@greatscottlab]

Great :-) I hope it was interesting.

[@ShahZahid]

electronoobs made a video on the same thing, this ic is really incredible, i have a handful laying around from a component kit, well ig ill put some of them to use, awesome video as always

[@greatscottlab]

Thanks :-)

[@intelligentprocessorai396]

Thanks a lot for this info... Brother!!! Now I can complete my mysterious project!!

[@greatscottlab]

Glad I could help!

[@thomasandrews9355]

Hey, not sure if saw the shout out from Dave's garage but you deserved it!!!

[@nicosyrjalainen1392]

What a coincidence. I'm just about to use this component in my LED project and could use a guide!

[@abdelrahmanmohsen2735]

we really enjoy your videos and wait for it . iam a fan of powersupplies too

[@justcallme00oogy]

Could someone help explain why the voltage is only pulled down to 2V and not near 0V at 3:58 when the transistor is turned on?

[@greatscottlab]

That is the collector emitter voltage drop of the transistor. It can not go lower due to this construction.

[@justcallme00oogy]

Oh I see that makes sense! Thanks!

[@TravisFabel]

its now 24 days since you posted this vid, and it was only suggested to me now... even though I'm subscribed and have the bell on.

[@avejst]

great video as always 👍😀 thanks for sharing your experience with all of us 👍😀

[@lasciencedelamusique6245]

You're really Great! Thank you for sharing all these cool tricks and valuable knowledge.

[@deathshaker0026]

Oh wow! It's very handy like a 555ic, and just as easy to use.

[@greatscottlab]

Yep👍

[@deathshaker0026]

@@greatscottlab I just had to order a bunch of them. Thank you for making the video.

[@kevgermany]

You really make me want to play with this stuff. Thanks.

[@change_your_oil_regularly4287]

Ordered a big bag of those a couple of months ago

[@omsingharjit]

0:40 the efficiently of transformer is also above 90 % equal to Smps so why smps only takes cradits of it 🤔🤔🙄🙄 ??

[@kennmossman8701]

a linear regulator versus a SMPS? NOT ALWAYS but generally SMPS are more efficient but do have a host of issues/problems.

[@onecircuit-as]

Brilliant! What a great vid - now I know what to do with this little guy. 👍😀

[@prasadvasu8462]

Lol I have been collecting many of these hoping to make something with them. Thanks!

[@romapanas921]

Hi. help me to understand why you chose the voltage drop on tl431 2.5v at 9:30 sec of the video? I thought there should be about 1.8v. Sorry for my english.

[@williammathew8395]

I once tried to build a switched mode power supply on my own.. but the capacitor smashed into my head( it exploded).. that event made me afraid of those...

[@vencdee]

Great video, one of best ever.

[@jonsimmons1284]

Great video, as usual, but I have always wanted to know what pens you use?

[@yourboi1842]

I literally need this component after watching this video it’s the thing I’m missing in my circuit