I once tried prototyping a 1A buck LED driver that operates at around 1 MHz on a bread board. This ultimately drove me to begin my bachelor's degree in electrical engineering because I had no idea why the heck this just wouldn't work! Today I do know why... =D
@@After_Tech_Industries To be honest, I never actually checked what was the problem. So "Today I have some ideas why" would have been more correct. I think the main reason was the high contact resistance in the bread board contacts along the high frequency, high current path. I think the losses there probably screwed up the feedback loop of the regulator. Another probable problem was that the MIC2301 driver chip that I used has an integrated high side switch and therefore its SOIC8 package has an ePad at the bottom for cooling. The SOIC adapter board I used didn't connect to that, of course. I think it then also overheated way more quickly than I expected.
I was researching the different topologies to decide which one to design a low-voltage DC UPS around, and kept hearing that SEPIC is unstable against transient loads. It'd be interesting to see a video on how different topologies react to different types of loads.
Hey sounds like the situation I found myself in too! Surprised there isn't more commercial options around this given how often you'd think home users would just want an uninterrupted DC power source for their home network and other DC-powered electronics. My setup at the moment is a small server rack with a 15V DC PSU and a 12V Lead Acid battery (+ battery tender) with their ground connections tied. The output voltages are separated by diodes, thus creating a sort of "OR-ing" device. That gate's output is connected to a powerpole rigrunner so that I can split all my components to separate SEPIC converters to ease the change in load and to also not have a single point of failure. So far so good but then again I'm only running raspberry pi's, switches, and a router at the moment.
My experience is any SMPS will be unstable with transient loads. Go ahead and use one, but either have a huge cap, a battery or some other stable transient source to keep it from blowing out your electronics, or add a linear low-drop-out regulator at the end. It could even run saturated for low loss, but will prevent the voltage from going too high. That said, I suspect this SEPIC is worse than most SMPSs.
Many power supplies are based on a dual control loop topology, with an outer loop with conventional voltage control PWM and inner loop based on current mode control. This tends to protect the power supply against transient loads, especially short circuits and the like. Something like UC3843 and like series of chips may be more stable with a SEPIC converter. There is a sense resistor in series with the source of the switch to control switch currents, and there is an outer control loop that senses the voltage.
@@chaosdragon6718 These are the reasons I moved away from SEPIC topology. I'm currently exploring flyback and push-pull, but stepping from designing buck converters to these more advanced topologies is pretty daunting.
Your videos are truly informative. It provides me with a lot of electronics knowledge as a hobbyist. Keep going. Also get well soon. You are great, scott :)
Sure, they're very nice. But I think there's an error on the schematics presented for the DIY SEPIC (on 10:20): there's no connection to gnd for Q1 (and L2, C4, C5).
SEPIC converters are great for applications where the output power is low. For higher power applications, there is the two-switch non-inverting buck-boost converter. It is simply a combination of a buck and a boost converter. When the input voltage is higher than the output, it holds the “boost” switch open and modulates the “buck” switch. When the input voltage is lower than the output, it holds the “buck” switch closed and modulates the “boost” switch.
What I like about this design is the "self destruct" protection capability: One of my biggest fears when using Buck Converters specifically is that, when the switching transistor fails, it will most likely go shortcircuit (which in buck converters means the full input voltage will get to the output) destroying the load with overvoltage. In contrast, this design will not only let the voltage go low but also may just blow a fuse or trigger an overcurrent protection. This feature/bug is also present in synchronous buck converters: if one transistor fails, as soon the second one turns on, the whole thing will just go shortcuit and trigger a protection system before the output voltage can get high enough to kill the load. But maybe I've too much of a green mind for a disposing culture society?
I love using SEPIC in my designs. The biggest benefit is that they are inherently failsafe, there is no fault mode in which the input voltage can be on the output. Also if you need positive and negative rails, you can use the same regulator chip for SEPIC and inverting.
There is a chance yes, but if I remember correctly from Siemens’ SN29500 the chance is relatively small. And then you can split up C1 to make the design even more robust.
Great video Scott! I suspect your ferrite toroid had issues due to saturation, due to the uni-directional currents in it. Either add a small gap by using a multi part core, or go with high permeability powdered iron.
Some years ago I designed and built my own SEPIC converter, and used an off-the-shelf part for coupled inductors with one core. Before I built it, I actually did simulations of coupled vs separate inductors and it helped the ripple out a bit. Once built, it worked quite well. My board also included a Ćuk converter which is basically when you take a SEPIC and swap the placement of the second inductor and diode, resulting in a negative voltage with very similar specs. Made for a nice stable+versatile bipolar +-12V supply.
Your definitely one of the most intelligent you tubers lol. Live your channel. When I finally get my parts replaced and back too work I’m definitely funding your channel lol. Ty for your time and research my friend.
I have alot of experience with SEPIC and Cuk converters. Coupled inductors are great. They can be more efficient (alot of variables there though), they have better dynamics (dual inductor SEPICs and Cuks have some high frequency resonance that can make compensation harder), and the overall solution size can be smaller than for dual inductors. What I've seen is for name brand (like Coilcraft and Wurth) inductors, prices are comparable between two singles and a coupled. But the market for singles is bigger, so its easier to find other manufacturers of singles. Also, worth pointing out that I've heard Dr Cuk is adamant that a Cuk converter built with a coupled inductors isn't really a Cuk converter.
@@Blox117 It's named for en.wikipedia.org/wiki/Slobodan_%C4%86uk . Funny name perhaps, but he's Serbian, that is his name, and that is indeed what it's called.
dude, the sepic is noesing as fk, but i have to use it, how to reduce the ripple to 5mv under 12v at 3a? i have tried everything........rc lc re apsorbtion, comm choke, what i did wrong? it keep around 100mv at 1a ar 12v, i cant knock it down further.......
It’s kind of amazing that buying two inductors is significantly cheaper than a single coupled one. I suppose there’s just not a big enough market for them to compete on price, huh? Super cool video! Especially the DIY circuit at the end.
I found a moderately high power (5a or 60w) buck/boost converter. What I found was a decrease in efficiency, increase in heat. My aim was to power 4g modem/router on boats, which operates in high temperatures (on sea, on summer, in Turkey). Boats are like cars, while engine is running voltage contains lots of jitter due to charging alternator. And just like cars, in small boats there is not a service battery, which means while engine is not running voltage is 12v. While starting the engine, voltage can drop down to 10v. While engine is running, there is a lot of noise (or jitter) and voltage is 14.4v. My solution was to use two coils, then a group of capacitors then a boost converter (increases the voltage to 15v) then a buck converter (reduces the voltage to 12v). 🤣😂 This devides the heat dissipation, reduces the jitter and just works... But in lower power applications (like 1-2amps) buck-boost converters works very nice.
This is a bit silly because the 4g modem/router internally has buck converters, which you obviously cannot get around, so you are forced to use this roundabout way. High freq, and highly integrated GaN buck-boost would have worked for you well, but this tech is not very widely available yet, and probably more expensive than chaining two very simple converters like you have done.
What happens to efficiency if you make it synchronous? I’d think you’d get it way more efficient. I’d love to see more videos on boost/buck with ultra high efficiency for sure.
Synchronous 4-switch devices are much more efficient and can handle much higher currents. Of course the down side is that they are much more expensive and are also becoming quite hard to find. My preference for stable voltages with very little ripple are ones based on the LTC3780, the output is so stable that I have very successfully used them for mobile radio, something which is near impossible with most non-linear converters. I realised early on that Sepic devices would not be adequate.
@@chrishartley1210 ya a full bridge is a solution but the problem with full bridges is that they require p channel high side which means you can’t use ganfets. I’m wondering if sepic with the diode replaced with another fet woold get you to n channel nirvana.
Thanks for All your video's. I have a SEPIC converter in Simulation program LTCad XVII. But NO matter WHAT i do, the current through the LOAD is Reversed. Till I saw this Video ! With D2 connected between Vcc and GND. NOW it Works ! Great Scott !
Nice video. I've been using these buck/boost converters in my projects for several years. They work great, and allow you to use almost any DC cube power supply without worrying about input voltage.
nice, often i see boost buck and sepics being combined IC that efficiency seems low tho at 60% a LDO may be better ( if it is lowering) Also maybe make a video about the energy efficiency of all those converters .
I actually built a SEPIC converter on a perfboard recently. It can output up to around 50W of power and comes with an efficiency of around 80-85%. Anyway, great and educational video!
There is a great document from Recom that explains all the topologies. There I learned about the coupled inductors. Somebody who klicked this video is probably interested in that document.
I think you can build a boost converter circuit on a perfboard but you must put the components much closer together, the distance you use wouldn't work properly on any PCB type I think. All datasheets of switching power supply IC's are always hammer on that you must keep the loops as short as possible.
Have you considered using a synchronous switching configuration rather than the diode? Perhaps that would give you a better efficiency payoff than using the coupled inductor.
using a transformer ensure 5percent increase, lossen coupled one gives anther 1percent boost, a llc typology needs pmos, or bootstrap, whichs means bad, really bad, especially in boost condition.......
( 1:21 & 6:22 ) I have used a SEPIC voltage converter that uses a coupled inductor and it has some decent efficiency and also has some protection features which is nice. The only concern I have is the EMI it might be producing specially I used mine on an audio amplifier build and it has some weird issues "sometimes" specially on its aux mode, might have to some tests on it to confirm those thingies.
For higher currents, a 4 switch buck-boost will always be the better solution. SEPIC (as well as inverting CUK type ) switches VIN+Vout on its switch node and carries the large du/dt EMI problem. And you switch more current than Iout. That to a much larger Hot loop which includes the SEPIC coupling capacitor. In essence, you store the complete transfer energy in the inductive components so those inductors have to be sized that way.
I'm thinking the Prof. Slobodan "Cuk" converter deserves a thorough review. Somewhere I have my first power supply kit I built, a SEPIC-Cuk split rail design to emulate a low power computer PSU and I'm trying to recall what specifically. Man, I forget, seems like something maybe SDR related though I forget. Neat design.
I have a DC to DC converter which have 3 inductors. Yeah. Its a buck boost converter but at the same time converts a single supply input into a double supply output. Its incredibly useful, but the problem is that it can output only 20w max. Is there a way to build such a circuit that can output a bigger amount of power like 200 or 400w? It can be incredibly useful to run POWERFUL audio amplifiers without transformer, just from a battery. Please, this is probably the most interesting voltage converter and in my opinion its worth giving it a shot. I used JLCPCB for the first time a few days ago and ordered some boards (layout made by me, schematic found on the internet and made better). They are 200w audio amplifiers but they require a double supply. Its propably possibile build one of those, but i cant design it unfortunately. Some online schermatics dont look so promising...
@@gianluca458 ciao Gian, ti scrivo in italiano che faccio prima. Non ho visto li schema me la teoria del potenziamento è questa: stesso schema, condensatori che portino tensioni e correnti di ripple maggiori, induttanze con valore leggermente minore e che portino più corrente, MOSFET con tensioni maggiori e Rds(on) adeguate alle nuove correnti in gioco e idem per i diodi. Se puoi mandarmi lo schema o ti servono altri consigli, io ci sono
Love your videos, it’s so simply explained yet very informative, I wish you could make more videos of coupled inductors since it’s a rare topic on the internet!
I'm looking at the schematic with coupled inductors and it appears if you remove the coupling capacitor you end up with a flyback converter. It just goes to show that all the different DC-DC converter topologies are actually very similar in operation.
Is this commercial Buck converters are coming with close loop control (I mean, is it change its duty according to the change in output voltage? As we know, the output voltage may change with change in load. Please, give your thoughts.) Thanks, in advance
That sounds like a constant current/constant voltage (CC/CV Buck) converter. The LM5117 is just one example, but I bought some cheaper ones from Amazon years ago because I needed constant current control for running LEDs. They use feedback loops to monitor current & voltage.
They use the smaller coil packages mainly for size savings and there has been an artificial standard for such converters because a few companies in China did massive runs pumping out near to a half million units and resellers flooding the markets like Amazon and eBay......they become so common that they just get copied
I would have thought the two coils in close proximity would couple anyway. Perhaps not as tightly/efficiently as two windings on the same ferrite ring, but... it's something?
Hello from Georgia, USA! I really appreciated this video. I do have a question that I would like to ask. I'm adding heated seats, grips, gloves, and primary clothing layers that will run off of my bike for cold weather riding. The bike has very little extra power so I'm changing all of my lights to LED and I want to use a solid state timer for the signals rather than simply adding resistors to prevent hyperflash. Most of the heated element controllers use a resistor for the lower temperature settings. It seems to me that I could use one of these boards to control the temp and actually conserve amps by using a lower setting If my gauge showed a constant draw on my battery rather than a 2a or so charge. Am I right. I'd use the FP5-139 to get the most out of each amp put out by my charging system.
I'd guess that a specific boost or buck circuit is more efficient, to take a simple example in a 12V to 24V boost, half the output power is coming directly from the input, while it's a bit less than half in a 12V to 5V buck
I made a boost converter using a 555ic and an irf540 mosfet. I used a sepic winding of 150uf. I could get 9v input 99v output. It was fun. I'd love to know what you think of it.
Damn... the comment section is moved again. As usual, great content, Scott ! Wish I could do something with this but nah, not even my profession neither my job, still watching this xD
12v li bms, booster oder Downer dran und damit an Lizellen um nen kompakten Batteriespeicher zu haben den man direkt an zB. 20V Solarpanel dran hängen kann.🤔.. 👉 also plug and play mässig.. Aufladbarer Akku den man mit standardhandylader 5v oder auch 12v Netz oder am Ziganz. Laden kann oder eben auch an bis zu 20v Solar. 👉 "ich denk zu einfach" 😋
Thanks for the video, it was very interesting to see a different approach, perhaps you can help me with a problem, I want to make an 18650 12v power supply to run an emergency LED light, so do I put three 18650 in series to give me my 12 volts or do I put my 18650 batteries in parallel to give me 3.7 volts and boost that voltage to 12 volts, any suggestions for the best method? Thanks, Bob in the UK
recent day I made my own sepic converter with xl6009, two 47uH inductor and a 1uF capacitor. It can deliver much more energy than I think and blow up my AO3400 and AO3401. and another interesting thing is it cannot work with usb because some usb power connection is poor and voltage can drop to 3.5V so the chip will not work properly
Would you be willing to build a bougie Hotwire foam cutter? There’s lots of tutorials on UA-cam, but they aren’t really very heavy duty and they don’t do a good job explaining how they work. I’d like to hear you explain the theory and show how to build a quality, robust foam cutter.
Again a great video. The explanations are really easy to follow and very well illustrated. What I was wondering though, is where the losses come from in this kind of circuit. Could the increase of the efficiency be traced back to the lower ESR from the coils maybe? The commercial ones had around 2 ohms and the DIY had a little less if I saw correctly. And how about the diode? What was the forward voltage there? It would be really interesting to see those values. Well, if the efficiency is of interest anyway.
Thanks for the hint. I started watching that video some time ago, but I guess I got interrupted. Good poonts for sure. I was nust curious about the efficiencies of the SEPIC architecture. So I started googling a little and found the following link which was quite interesting as well. Even more since the efficiency ratio was similar. However, I am only a part time electrical engineer, so whenever words like resonance and crest factor, its becoming too involved for me xD Having a converter which is able to go higher and lower than the supply voltage just sounded too comfortable. www.electro-tech-online.com/threads/sepic-converter-is-only-67-efficient-why-so-bad.132702/
I once tried prototyping a 1A buck LED driver that operates at around 1 MHz on a bread board.
This ultimately drove me to begin my bachelor's degree in electrical engineering because I had no idea why the heck this just wouldn't work!
Today I do know why... =D
What wasn't working?
I presume that it might have been the frequency; but I still want to know!
@@After_Tech_Industries To be honest, I never actually checked what was the problem. So "Today I have some ideas why" would have been more correct.
I think the main reason was the high contact resistance in the bread board contacts along the high frequency, high current path. I think the losses there probably screwed up the feedback loop of the regulator.
Another probable problem was that the MIC2301 driver chip that I used has an integrated high side switch and therefore its SOIC8 package has an ePad at the bottom for cooling. The SOIC adapter board I used didn't connect to that, of course. I think it then also overheated way more quickly than I expected.
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I was researching the different topologies to decide which one to design a low-voltage DC UPS around, and kept hearing that SEPIC is unstable against transient loads. It'd be interesting to see a video on how different topologies react to different types of loads.
Hey sounds like the situation I found myself in too! Surprised there isn't more commercial options around this given how often you'd think home users would just want an uninterrupted DC power source for their home network and other DC-powered electronics. My setup at the moment is a small server rack with a 15V DC PSU and a 12V Lead Acid battery (+ battery tender) with their ground connections tied. The output voltages are separated by diodes, thus creating a sort of "OR-ing" device. That gate's output is connected to a powerpole rigrunner so that I can split all my components to separate SEPIC converters to ease the change in load and to also not have a single point of failure. So far so good but then again I'm only running raspberry pi's, switches, and a router at the moment.
My experience is any SMPS will be unstable with transient loads. Go ahead and use one, but either have a huge cap, a battery or some other stable transient source to keep it from blowing out your electronics, or add a linear low-drop-out regulator at the end. It could even run saturated for low loss, but will prevent the voltage from going too high.
That said, I suspect this SEPIC is worse than most SMPSs.
Many power supplies are based on a dual control loop topology, with an outer loop with conventional voltage control PWM and inner loop based on current mode control. This tends to protect the power supply against transient loads, especially short circuits and the like. Something like UC3843 and like series of chips may be more stable with a SEPIC converter. There is a sense resistor in series with the source of the switch to control switch currents, and there is an outer control loop that senses the voltage.
@@chaosdragon6718 These are the reasons I moved away from SEPIC topology. I'm currently exploring flyback and push-pull, but stepping from designing buck converters to these more advanced topologies is pretty daunting.
There is also a four-switch buck-boost converter. Maybe look at BQ25713 for an example.
Your videos are truly informative. It provides me with a lot of electronics knowledge as a hobbyist. Keep going. Also get well soon. You are great, scott :)
Thanks a ton
@@greatscottlab I'm so glad that you replied to my comment 😊
@@greatscottlab what is the amps of this and could I safely use something like this with a 12 volts 20 watts solar panel?
Sure, they're very nice. But I think there's an error on the schematics presented for the DIY SEPIC (on 10:20): there's no connection to gnd for Q1 (and L2, C4, C5).
Another great video.
SEPIC converters are great for applications where the output power is low. For higher power applications, there is the two-switch non-inverting buck-boost converter. It is simply a combination of a buck and a boost converter. When the input voltage is higher than the output, it holds the “boost” switch open and modulates the “buck” switch. When the input voltage is lower than the output, it holds the “buck” switch closed and modulates the “boost” switch.
it will be priblematic in between, .....
What I like about this design is the "self destruct" protection capability:
One of my biggest fears when using Buck Converters specifically is that, when the switching transistor fails, it will most likely go shortcircuit (which in buck converters means the full input voltage will get to the output) destroying the load with overvoltage. In contrast, this design will not only let the voltage go low but also may just blow a fuse or trigger an overcurrent protection.
This feature/bug is also present in synchronous buck converters: if one transistor fails, as soon the second one turns on, the whole thing will just go shortcuit and trigger a protection system before the output voltage can get high enough to kill the load.
But maybe I've too much of a green mind for a disposing culture society?
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I love using SEPIC in my designs. The biggest benefit is that they are inherently failsafe, there is no fault mode in which the input voltage can be on the output. Also if you need positive and negative rails, you can use the same regulator chip for SEPIC and inverting.
C1 fails short.
There is a chance yes, but if I remember correctly from Siemens’ SN29500 the chance is relatively small.
And then you can split up C1 to make the design even more robust.
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Great video Scott! I suspect your ferrite toroid had issues due to saturation, due to the uni-directional currents in it. Either add a small gap by using a multi part core, or go with high permeability powdered iron.
Ah yes another great scott video!
Awesome video,very informational about the sepic convertor!
Glad you enjoyed it!
Some years ago I designed and built my own SEPIC converter, and used an off-the-shelf part for coupled inductors with one core. Before I built it, I actually did simulations of coupled vs separate inductors and it helped the ripple out a bit. Once built, it worked quite well. My board also included a Ćuk converter which is basically when you take a SEPIC and swap the placement of the second inductor and diode, resulting in a negative voltage with very similar specs. Made for a nice stable+versatile bipolar +-12V supply.
Your definitely one of the most intelligent you tubers lol. Live your channel. When I finally get my parts replaced and back too work I’m definitely funding your channel lol. Ty for your time and research my friend.
Awesome! Thank you!
@@greatscottlab Next project Cuk Converter pleaseeeeee
I have alot of experience with SEPIC and Cuk converters. Coupled inductors are great. They can be more efficient (alot of variables there though), they have better dynamics (dual inductor SEPICs and Cuks have some high frequency resonance that can make compensation harder), and the overall solution size can be smaller than for dual inductors. What I've seen is for name brand (like Coilcraft and Wurth) inductors, prices are comparable between two singles and a coupled. But the market for singles is bigger, so its easier to find other manufacturers of singles. Also, worth pointing out that I've heard Dr Cuk is adamant that a Cuk converter built with a coupled inductors isn't really a Cuk converter.
lol "cuk"
@@Blox117 It's named for en.wikipedia.org/wiki/Slobodan_%C4%86uk . Funny name perhaps, but he's Serbian, that is his name, and that is indeed what it's called.
@@Blox117 Apparently it's pronounced 'chook'
@@triffid0hunter oh i see, there is an accent mark
dude, the sepic is noesing as fk, but i have to use it, how to reduce the ripple to 5mv under 12v at 3a? i have tried everything........rc lc re apsorbtion, comm choke, what i did wrong? it keep around 100mv at 1a ar 12v, i cant knock it down further.......
Another great video!
What I always love , is the use of paper, pen and markers!
3:00 your Bosch washing machine is done.
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Your videos are delightfully concise with surprising details and always inspire greater things
pm me can you to install do sola paint of charger*
It’s kind of amazing that buying two inductors is significantly cheaper than a single coupled one. I suppose there’s just not a big enough market for them to compete on price, huh?
Super cool video! Especially the DIY circuit at the end.
Winding a single is much easier than winding a dual with most winding machines.
This is without doubt a very useful project
Glad you think so!
I found a moderately high power (5a or 60w) buck/boost converter. What I found was a decrease in efficiency, increase in heat. My aim was to power 4g modem/router on boats, which operates in high temperatures (on sea, on summer, in Turkey). Boats are like cars, while engine is running voltage contains lots of jitter due to charging alternator. And just like cars, in small boats there is not a service battery, which means while engine is not running voltage is 12v. While starting the engine, voltage can drop down to 10v. While engine is running, there is a lot of noise (or jitter) and voltage is 14.4v.
My solution was to use two coils, then a group of capacitors then a boost converter (increases the voltage to 15v) then a buck converter (reduces the voltage to 12v). 🤣😂 This devides the heat dissipation, reduces the jitter and just works...
But in lower power applications (like 1-2amps) buck-boost converters works very nice.
This is a bit silly because the 4g modem/router internally has buck converters, which you obviously cannot get around, so you are forced to use this roundabout way.
High freq, and highly integrated GaN buck-boost would have worked for you well, but this tech is not very widely available yet, and probably more expensive than chaining two very simple converters like you have done.
Although I'm not an electronics guy, I like your videos a lot, because they are very informative and understandable.
You have some of the best electronics videos.
Thanks :-)
I would love to see a video about vacuum flourescent displays!
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What happens to efficiency if you make it synchronous? I’d think you’d get it way more efficient. I’d love to see more videos on boost/buck with ultra high efficiency for sure.
Synchronous 4-switch devices are much more efficient and can handle much higher currents. Of course the down side is that they are much more expensive and are also becoming quite hard to find.
My preference for stable voltages with very little ripple are ones based on the LTC3780, the output is so stable that I have very successfully used them for mobile radio, something which is near impossible with most non-linear converters. I realised early on that Sepic devices would not be adequate.
@@chrishartley1210 ya a full bridge is a solution but the problem with full bridges is that they require p channel high side which means you can’t use ganfets. I’m wondering if sepic with the diode replaced with another fet woold get you to n channel nirvana.
@@jameshancock The 3780 (and 3789) drives 4 N-channel MOSFETs.
@@chrishartley1210 wow. Gotta see how they do that because a pump can’t work so how are they keeping the top fets open 100% of the time?
Fantastic video, dude! Thanks a lot! 😃
I'm definitely going to look around for those!!!
Stay safe and creative there! 🖖😊
Thanks! You too!
Thanks for All your video's.
I have a SEPIC converter in Simulation program LTCad XVII.
But NO matter WHAT i do, the current through the LOAD is Reversed.
Till I saw this Video ! With D2 connected between Vcc and GND.
NOW it Works ! Great Scott !
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Nice video. I've been using these buck/boost converters in my projects for several years. They work great, and allow you to use almost any DC cube power supply without worrying about input voltage.
nice, often i see boost buck and sepics being combined IC
that efficiency seems low tho at 60% a LDO may be better ( if it is lowering)
Also maybe make a video about the energy efficiency of all those converters .
TL494 is awesome choice.
You can even make ~240V DC boost to drive vacuum tubes. Not recommend for beginners, but you can check out Mr Carlson's Lab.
Also USB 1-30V CC CV converters are using SEPIC topology. They are really handy to use, but the efficiency is about 60%
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Sir i love your hand writing
I actually built a SEPIC converter on a perfboard recently. It can output up to around 50W of power and comes with an efficiency of around 80-85%. Anyway, great and educational video!
pm me can you to install do sola paint of charger*
There is a great document from Recom that explains all the topologies.
There I learned about the coupled inductors. Somebody who klicked this video is probably interested in that document.
I think you can build a boost converter circuit on a perfboard but you must put the components much closer together, the distance you use wouldn't work properly on any PCB type I think. All datasheets of switching power supply IC's are always hammer on that you must keep the loops as short as possible.
Hi Scott! Thank You for all the GREAT videos!! :-)
Great shot, Scott!!! Thanks.
Have you considered using a synchronous switching configuration rather than the diode? Perhaps that would give you a better efficiency payoff than using the coupled inductor.
using a transformer ensure 5percent increase, lossen coupled one gives anther 1percent boost, a llc typology needs pmos, or bootstrap, whichs means bad, really bad, especially in boost condition.......
Eagerly looking forward for next episode of "Diy or buy" as frequency modulator ( FM radio)
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2:59 that scared me🤣
I thought it was something in my room
( 1:21 & 6:22 ) I have used a SEPIC voltage converter that uses a coupled inductor and it has some decent efficiency and also has some protection features which is nice. The only concern I have is the EMI it might be producing specially I used mine on an audio amplifier build and it has some weird issues "sometimes" specially on its aux mode, might have to some tests on it to confirm those thingies.
pm me can you to install do sola paint of charger*
For higher currents, a 4 switch buck-boost will always be the better solution.
SEPIC (as well as inverting CUK type ) switches VIN+Vout on its switch node and carries the large du/dt EMI problem. And you switch more current than Iout. That to a much larger Hot loop which includes the SEPIC coupling capacitor. In essence, you store the complete transfer energy in the inductive components so those inductors have to be sized that way.
pm me can you to install do sola paint of charger*
Hey, your voice sounds like you are (recovering) from sickness. I wish you the best!
I'm thinking the Prof. Slobodan "Cuk" converter deserves a thorough review. Somewhere I have my first power supply kit I built, a SEPIC-Cuk split rail design to emulate a low power computer PSU and I'm trying to recall what specifically. Man, I forget, seems like something maybe SDR related though I forget. Neat design.
The LM based ones works fine down to 3V the XL based starts to have issues below 3.8 volts, don't use it if you are using an input range below 3.8V.
The SEPIC buck-boost design is more elegant than I expected it to be.
look for LTC3780 based boards, it's not SEPIC but it does buck and boost work
Outstanding videos in every aspect AGAIN.
I truly respect you.
Thanks mate :-)
I have a DC to DC converter which have 3 inductors. Yeah. Its a buck boost converter but at the same time converts a single supply input into a double supply output. Its incredibly useful, but the problem is that it can output only 20w max.
Is there a way to build such a circuit that can output a bigger amount of power like 200 or 400w?
It can be incredibly useful to run POWERFUL audio amplifiers without transformer, just from a battery. Please, this is probably the most interesting voltage converter and in my opinion its worth giving it a shot.
I used JLCPCB for the first time a few days ago and ordered some boards (layout made by me, schematic found on the internet and made better). They are 200w audio amplifiers but they require a double supply.
Its propably possibile build one of those, but i cant design it unfortunately. Some online schermatics dont look so promising...
Can you give me a link?
Whoops, some of it is written in italian.
The link works.
I Wonder how this circuit behaves
@@gianluca458 use external mosfets + heatsinks
The schematic May be ok and i can be wrong...
@@gianluca458 ciao Gian, ti scrivo in italiano che faccio prima. Non ho visto li schema me la teoria del potenziamento è questa: stesso schema, condensatori che portino tensioni e correnti di ripple maggiori, induttanze con valore leggermente minore e che portino più corrente, MOSFET con tensioni maggiori e Rds(on) adeguate alle nuove correnti in gioco e idem per i diodi.
Se puoi mandarmi lo schema o ti servono altri consigli, io ci sono
Excellent video, Scott!
I am now familiar with the SEPIC controller.
That was my plan :-)
So informative , Thanks a lot man
Greetings from Germany
and from southern part of Bayern
Greeting back ;-)
Great video Scott. I learned a ton. Next week your prototype PCB will be shipped by your sponsor JLC PCB I guess ;-)
Awesome and very well explained. Great Sunday afternoon entertainment !
Awesome :-)
Love your videos, it’s so simply explained yet very informative,
I wish you could make more videos of coupled inductors since it’s a rare topic on the internet!
I'm looking at the schematic with coupled inductors and it appears if you remove the coupling capacitor you end up with a flyback converter. It just goes to show that all the different DC-DC converter topologies are actually very similar in operation.
pm me can you to install do sola paint of charger*
Maybe build a full H bridge buck boost converter with one inductor for comparison?
Absolutely yes, I think that the king of the buck-boost converters is the 4 switch one
Is this commercial Buck converters are coming with close loop control (I mean, is it change its duty according to the change in output voltage? As we know, the output voltage may change with change in load. Please, give your thoughts.) Thanks, in advance
That sounds like a constant current/constant voltage (CC/CV Buck) converter. The LM5117 is just one example, but I bought some cheaper ones from Amazon years ago because I needed constant current control for running LEDs. They use feedback loops to monitor current & voltage.
Get well soon brother ❤️🔥
My voice is already much better :-) Thanks.
Danke!
Thank you very much for the support :-)
Yeah we always using convoto on our projects.
They use the smaller coil packages mainly for size savings and there has been an artificial standard for such converters because a few companies in China did massive runs pumping out near to a half million units and resellers flooding the markets like Amazon and eBay......they become so common that they just get copied
I would have thought the two coils in close proximity would couple anyway. Perhaps not as tightly/efficiently as two windings on the same ferrite ring, but... it's something?
I am your big fan great scott
Please explain where the input and output are located on SEPIC
You generally need lower inductance if you used a coupled inductor. It isn't just the efficiency but also space reduction :)
pm me can you to install do sola paint of charger*
Love your channel!
qestion: can you make a cheap/ceapish "garden light mppt "low Voltage battery/supercap?
awesome. use this all the time. finally learned how they work
Great to hear!
I was wondering if I could use a filter choke as a coupled inductor?
Very interesting! What other buck-boost converter designs are there that are more efficient?
Dahono converters?
I had couple of that buck converter all fried when i connect 3.7v lithium battery
Very good video Mr Scott.
Great video. Can you compare the SEPIC with the non inverting buck-boost to see which one is mor efficient? Thanks.
its fun to build at home i will try it😀😃
Awesome :-)
This may? work for super efficient solar lights
Hello from Georgia, USA! I really appreciated this video. I do have a question that I would like to ask. I'm adding heated seats, grips, gloves, and primary clothing layers that will run off of my bike for cold weather riding. The bike has very little extra power so I'm changing all of my lights to LED and I want to use a solid state timer for the signals rather than simply adding resistors to prevent hyperflash.
Most of the heated element controllers use a resistor for the lower temperature settings. It seems to me that I could use one of these boards to control the temp and actually conserve amps by using a lower setting If my gauge showed a constant draw on my battery rather than a 2a or so charge.
Am I right. I'd use the FP5-139 to get the most out of each amp put out by my charging system.
Informative as always! Thanks mate!
I'd guess that a specific boost or buck circuit is more efficient, to take a simple example in a 12V to 24V boost, half the output power is coming directly from the input, while it's a bit less than half in a 12V to 5V buck
I made a boost converter using a 555ic and an irf540 mosfet. I used a sepic winding of 150uf. I could get 9v input 99v output. It was fun. I'd love to know what you think of it.
555 ic in not efficient for this type of circuit
Damn... the comment section is moved again.
As usual, great content, Scott !
Wish I could do something with this but nah, not even my profession neither my job, still watching this xD
Thanks man
You're welcome!
Your DIY schematic seems to be missing a ground on the Q1 L2 node.
True
12v li bms, booster oder Downer dran und damit an Lizellen um nen kompakten Batteriespeicher zu haben den man direkt an zB. 20V Solarpanel dran hängen kann.🤔.. 👉 also plug and play mässig.. Aufladbarer Akku den man mit standardhandylader 5v oder auch 12v Netz oder am Ziganz. Laden kann oder eben auch an bis zu 20v Solar. 👉 "ich denk zu einfach" 😋
el circuito que armas ????? esta subido en algun lado? quisiera ver el feedback de tension
Please make a video on ACTIVE BMS
Amazing channel, super video!!
Thank you very much!
Thanks for the video, it was very interesting to see a different approach, perhaps you can help me with a problem, I want to make an 18650 12v power supply to run an emergency LED light, so do I put three 18650 in series to give me my 12 volts or do I put my 18650 batteries in parallel to give me 3.7 volts and boost that voltage to 12 volts, any suggestions for the best method?
Thanks, Bob in the UK
I thought my NAS beeped at 2:58 and 7:59 due to power reset or error. Then 8:39 made me check whether it's from this video
recent day I made my own sepic converter with xl6009, two 47uH inductor and a 1uF capacitor. It can deliver much more energy than I think and blow up my AO3400 and AO3401. and another interesting thing is it cannot work with usb because some usb power connection is poor and voltage can drop to 3.5V so the chip will not work properly
Would you be willing to build a bougie Hotwire foam cutter? There’s lots of tutorials on UA-cam, but they aren’t really very heavy duty and they don’t do a good job explaining how they work. I’d like to hear you explain the theory and show how to build a quality, robust foam cutter.
I have a bunch of those step up buck converters
This is rocket science.
I also build my own dcdc converter
Very enjoyable video. Best regards Chris
Glad you enjoyed it
Nice
Power output up to 10kw (for multiple microseconds)
thx for ur videos. will watch
Perfect video! Thank you!:DDD
Great.. too much information..i learn new..thanks a lot for such a good video..
Again a great video. The explanations are really easy to follow and very well illustrated.
What I was wondering though, is where the losses come from in this kind of circuit. Could the increase of the efficiency be traced back to the lower ESR from the coils maybe? The commercial ones had around 2 ohms and the DIY had a little less if I saw correctly.
And how about the diode? What was the forward voltage there? It would be really interesting to see those values. Well, if the efficiency is of interest anyway.
Watch my video about synchronous converters ;-)
Thanks for the hint. I started watching that video some time ago, but I guess I got interrupted. Good poonts for sure. I was nust curious about the efficiencies of the SEPIC architecture. So I started googling a little and found the following link which was quite interesting as well. Even more since the efficiency ratio was similar.
However, I am only a part time electrical engineer, so whenever words like resonance and crest factor, its becoming too involved for me xD
Having a converter which is able to go higher and lower than the supply voltage just sounded too comfortable.
www.electro-tech-online.com/threads/sepic-converter-is-only-67-efficient-why-so-bad.132702/
Diode losses and especially the inductors' ESR
As mentioned in the synchronous converters video, it is quite a bit more complex than just the ESRs and the diode losses. But yes.
Unfortunately you didn't link the more efficient one in the video description. Would appreciate.
It is not available anymore. Sorry. Use the XL6009 as the alternative.
Hellow
Very good really
I won't circuit of control of brushes motor drill
If you have
Thank you for good vedio
¡Gracias!
Thank you so much for the support :-)