This is hands down the best circuit design and simulation video I’ve seen. Your ability to take us step by step through each circuit then compare the theory to practical application is amazing. I hope you continue to make videos like this. I’m still an old guy beginner in the EE and RF fields. I learned more in your 13 min video than from hours of videos trying to explain the same circuits. Thanks!!!
This was absolutely brilliant! I really enjoyed your explaination on the push pull circuit, as well as the demonstration on the effects of the 220 pf capacitor on the BC557 base. Liked and Subscribed!
@@smartpowerelectronics8779 It would have been interesting to see the effects of a corresponding 220pF capacitor in the first circuit. I wouldn't expect a great improvement because the mosfet input capacitance is still charging through a 1K resistor, giving a typical time constant around 2μs with an IRFZ44, but it is not an expensive addition and you would then be comparing the three circuits on a rather more equal footing.
On the second two circuits there are some improvements you can make. If you split the 2K resistor to make it two 1K in series and run a capacitor to the output of your gate driver stage, you can get the switching times to be a bit faster. Adding an inductor in series with the 2K will also work but inductors cost more. The reason this works is because it causes the current in the lower 1K to not start changing until after most of the switching action is over. On your 3rd circuit a small schottky in place of the 1N4148 does two things for you. The 1N4148 has a recovery time so when the MOSFET is to be switched on, there is a brief delay before the upper NPN starts to do its thing. Also with the lower drop of a small schottky, the gate of the MOSFET is closer to ground.
@@bartios The reason for the 1N4148 is so that when the lower transistor is off, the upper one gets turned on. The delay in which is on really is a matter of his wording to explain the action. He is taking the voltage on the collector of the lower transistor as rising at some speed.
sounds like you know what your talking about ! the science of fast switching is quite meticulous here ! can you recommend a good fast gate driver that i can just buy already made ? : )
I am an electronics designer, or at least I attempt to be smart in electronics which I have learned that I some times fail to be :-) I have to say that I realy likes your clean way of explaining things up to a level that I share your videos to other designers that I work with, where we like to share clever tricks with each other.
Thank you, Werner! Yes, as a hobbyist an IC is easier and less prone to mistakes. These circuits are actually used in mass production in very high volumes because IC's are -believe it or not-more expensive than this bunch of smd parts...
Excellent. Much appreciate the time and effort that went into making this video (and others). Concise, clear and absolutely fascinating - I have a degree in Electrical and Electronic Engineering from UCL in England, but still find this channel to be educational and insightful.
@@smartpowerelectronics8779 yeah, its a nice little challenge for me ! and i chose the cascode circuit because you said its faster than light ! : P hehe. and sharp on/ off times is what im looking for !! the parts will arrive soon. and i have also bought the gate driver chip you suggested as well. i also had a new nano board arrive today ! so i can trigger the gate driver chip soon and also use my hall sensors now ! and this way i wont be over voltage'ing the gate ! good luck to me ! ha thanks !
Than you Berhard! Electronics is a great hobby, started at 10 yours old with a flipflop blink light which I wanted for my electric train, now 56 made my job out of it, but still tinker around in my free time!
Super thumbs-up! I especially like the summary chart where we can compare the three circuits side-by-side. Explain the 100 nf capacitor; what does SPICE show when the 100 nf capacitor is in/out of the circuit.
thanks for these valuable practical electronic lessons, it was beneficial, please make more of such videos in which every circuit is validated with real test
That takes me back. Used Simetrix for many years. I think it was the very best simulator. Also used the cascode driver for switching PSU designs back in the mid 80’s and was still using it for motor PWM driving in the 2000’s. The only downside is the addition voltage drop of the diode. Maybe not a problem for home electronics but it was a problem in automotive design when high current draw could cause local ground shifts.
Another well presented video for us electronics learning & exploring enthusiasts. Thank you very much for making such a good video and sharing your knowledge ❤
Excellent! I often have a 3.3V logic level and have difficulty driving a MOSFET with it. For the third circuit I would connect a 12V Zener diode to the collector of the BC547 and cathode of the 1N4148 to GND. This would limit the voltage to around 12V. The base of the upper transistor does not go above 12V and therefore neither does the emitter. The upper transistor would also not become saturated and would therefore switch off more quickly. But it is difficult to predict the current through the Zener diode.
I like your solution. The zener current is best predicted with a "if the current doesn't go elsewhere" sort of thinking. The current in the pull up resistor always has to go somewhere. Also: If you use two resistors in series as the pull up and run a small capacitor from the mid point over to the emitter of the upper transistor, you can use a much higher value resistor for the upper one. You only need much base drive to the upper transistor when you are in the process of turning on the MOSFET. The small capacitor stops the base drive from decreasing right at the time you dealing with the miller effect.
after experimenting with first example i found params for better delay: resistor 2.2k -> 100, parallel (to 4.7 resistor) cap 1n. on delay - 200ns, off delay - 310ns. also tried with diode after 2.2k resistor, delays almost the same
Thanks HansBaier! The speedup cap will help, but not too much because the the switch on of the MOSFET is sooo long ~2600ns, a few 100 ns does not help too much. :-)
Thank you JessieKropp!...well only one more Transistor at the input, but that causes extra delay. To prevent starup flash I choose a GPIO which has no other function and set it to high first thing in your setup(), works OK for ESP8266 and AVR arduino boards.
Folllow #3 with a totem-pole for even more current, up into the 10A range even. That’s better than most monolithic gate drivers, though there’s nothing stopping you from just putting a totem-pole (or ZXGD300_) after a monolithic gate driver.
Thx ScroganY. You are absolutely right, the totem pole will not add much delay and can further boost the gate current. By the way BC547/557's are not the best switching bjts, I was surprised how well they stood up to the task ;-)
Good analysis of an area of circuit design which is surprisingly difficult to optimize. The Miller capacitance also works against you and becomes a big issue with high voltage switching.
Yes, at higher voltages that is an additional reason to not even bother with the simple resistor pull up drive. Also: "super junction" MOSFETs are much better for high voltage. Even with 1000V on the drain, the gate acts as though the drain only went up to about 200V. For those who don't know: Internally a super junction MOSFET is a lot like a normal one but some P doped silicon extends further down into the bulk of the device. This P doped silicon looks like the gate of a great big JFET wired in cascode with the MOSFET. This spreads out the voltage gradient in the silicon making 1600V parts possible and also means that the full drain voltage happens at a place further from the gate.
Came up with that cascode cct for a commercial product back in 1981 and was rather pleased with it. Then a bit later I found it in a Philips publication that may have just predated it.
Really!? Cool I used "real" cascode in CFL's at the company you just mentioned: a low voltage MOSFET switching off the emitter of a power bipolar which has its base connected to 12V with a resistor.
Just use a IRLZ44 it’s the upto 5v gate version. I run it straight off of the arduino pin and common ground. It only uses voltage to se itch on or of so no issues with current.
There is always a little current required to overcome the gate capacitance, but charging and discharging a few picofarads directly from the Arduino is usually fine, I've done it to around 30kHz without issues.
That cascode drive is smart but has big issues, especially when done in a pullup like this. 1. The output is high when no input is present, so your gate will be high until your MCU boots up. This can be fixed by connecting a pullup resistor to your gate driver input. Also that means it's inverted. 2. BJT's saturate and make high speed drive for dc-dc converters a pain. (high dead time, delay and all that) 3. The drive is non symmetrical, so you can have good turn off and bad turn on and vice versa. I've played with these gate drives a lot and push-pull is my go-to for now if i want predictable timings ;)
One comment on the schematics for rather figurative reasons hinting at an engineering necessity: the emitter of the lower BC547 should be drawn with a line directly to the source of the iRFZ44. The idea behind it: The electric connection should also be as short as possible to minimize ground spike effects. Very nice solution though. Congrats!
Dankjewel! I also did not expect that the bas-cap would have so much impact, maybe it is because I use BC547's which are not really suitable for switching applications (but every hobbyist has some lying around...) Gelukkig Nieuwjaar!
why using 1% duty cycle? What will happen if w use 50% or more? Power losses will stay same? And will that going to allow us higher frequency (more 10Khz) to operate the first circuit?
I actually use 99% duty cycle, so the load is 99% of the time on in the simulation. 99% results in the maximum loss (conduction + switching loss) For the first circuit the ELECTRICAL limit is the on/off time which is in the range of 2.5µsec, so you can go to 100kHz at 50% duty cycle, 5µsec on/off. Thermally 100kHz at 50%is NOT ok because the switching losses will be too high. Hence 10kHz is the maximum.
@@smartpowerelectronics8779 Hi, thank you for the explanation, very helpful. One more question, is it possible to calculate the gate driver efficiency? And also can we use MOSFET instead of BJT in the level shifter?
Am I right with my guess that a bipolar transistor is used instead of a small mosfet like the BS170 because the driver transistor's switch time doesn't matter much compared to the power MOSFET's switch time?
Thank you! The IO should be ok, the 220pF causes a minor extra loss of 0.5*C*V^2*freq ~ about 30µW? There is another solution called "baker Clamp" with a Schottky Diode over b-c but I did not try that.
@@smartpowerelectronics8779 I have done Baker Clamp circuits. They do get rid of the storage delay but they don't help on the miller. Also just a schottky means that you now have the added capacitance of the schottky in the miller effect. Baker clamps end up complicated in real life. Also if you have a TN0629-N3 in place of the lower NPN, you can save some parts.
hi, great tutorial. I apologize if this is very basic knowledge I'm missing, but why can't we directly connect the MCU's GPIO pin to the gate of the MOSFET? MOSFETs have insulated gates so they won't draw any (or perhaps very little) current, right? much less than the base of a bipolar transistor for sure; so why go through the trouble of connecting a separate NPN for example in the first circuit? Thanks.
Stupid question: What would occur if we introduce a parallel capacitor to the resistor on the PWM signal line? In the second diagram, you've shown that the capacitor diminishes the switching delay, so couldn't we enhance the first diagram by including a basic capacitor? This would also ensure that the signal logic is consistent across all three diagrams...
One thing that can be done is to NOT shut-off the bipoar transistors totally. Keep them biased just a little and the charge time on the base will decrease. If you do so, the circuits can run easily 10x faster. I have made circuts with BC107 with respond time in nano second region by just letting them be biased instead of having the gate totally discharged.
Yes you are right, bipolar transistors can run really fast if they are not saturated, I mean, you can make FM transmitters at 100MHz with them! For power supplies, you do want to drive them in saturation to get as much current out of them as possible, this will slow down switch-off but it is still fast enough for the "low" switching frequencies of power supplies of 50-100kHz. So it is a trade off. By the way I have good memories of BC107's in metal can, I used 2 to solder my first blinky-light as a kid, no idea how it worked, just followed the magazines' instructions but that was what sparked my interest in electronics 🙂
@@smartpowerelectronics8779 Thanks for your excellent videos. It wasn't intended as criticism on your video, it was purely intended for the viewers do go further in their own investigations.
so ive got my hall sensor triggering my arduino and then arduino into a gate driver chip and then gate driver chip into a mosfet. but the coils are being turned on for wayy to long and its over heating the coils very quickly and not even getitng up to speed, very un smooth, i have a 100 ohms resistor between gate and driver output and10k across gate/source. and a 4k7 ohm reisstor between arduino out and gate driver logic input. can you suggest what im doing wrong here ??
Nice video and thanks for uploading. Just one question though. You say these circuits invert the logic signal.... but... If the input voltage is high with respects 0V then the MOSFET is off and the output voltage is high with respects to 0V too. Doesn't that mean the circuit Does not invert the signal? (In terms of Voltage)
The signal driving the mosfet gate is inverted with respect to the MCU signal driving the first transistor. Of course, the mosfet will also invert the signal applied to its gate, which means its drain will go high when the input from the MCU goes high. The two stages together indeed do not invert the signal. It's hopefully obvious, though, that the drain is high when the mosfet is off, and therefore no current passes through the load.
Hello, thanks for your video can you explain the choice of the BJTs for this push pull, I am trying with BJTs that have Ic=10A and I can't get a good signal at the output. 2SCR582D3 for the NPN and 2SAR582D3 for the pnp. Thanks
Do you have anything on driving a high side mosfet without resorting to having to use a p channel mosfet? I came up with one circuit, but it involves an extra 12 volts added on to the supply voltage, and having the transistors running at those high voltages.
If you want to drive the N channel, you are going to need those higher voltages. They do make chips that contain charge pumps for doing just that but if you want to go with common parts, there are tricks. If the switch is being driven with a duty cycle, you have a squarewave somewhere to drive a charge pump.
@@PainterVierax My comment was intended largely in humor. The idea is that fans of the 555 will tell you that you can do anything with it. There are a really large number of things that I have done with a 555 including a radio transmitter and stuff like that.
@@kensmith5694 yeah 555 fans are excessive. The IC is very versatile but it has severe limitations as well and it's not that easy to configure. It does the job but rarely worth it as a square or PWM emitter nowadays.
simetrix, free version, max 140 nodes. www.simetrix.co.uk/ There are also real free simulators like LTSpice, but I happen to be a little familiar with this one.
Nice circuits! My only concern is that these are all negative true, so when power is first applied and the Arduino hasn't yet fully booted, there may be a momentary period where the output is on. Any thoughts on how to prevent that?
You are right, so you need to check the starting conditions. You can also add a pull up resistor to the base of the transistor connected to the arduino to make sure it is high at startup.
Great video! Thanks for all the detail. I was looking again at electronics design to repair some modules I invested in to charge my Prius HV batteries if needed from sitting to long. Possibly use as a battery tender as well. Anyways, this got me thinking some more about control of the H bridge of the other gen 2 and gen 3 inverter converter assemblies I got from the salvage yards since I couldn't believe they were so cheap, like $20 for some of them at one time when the 50% off sale and even then about $75US then at most before half priced. The gen 2 inverter converter assembly is more modularized and seems based on the specs can more easily make a universal pure since wave inverter for whatever rectified generator inputs within spec input range. Plus have the three phase option. Seems can also be controlled to make a multifunction welder and maybe also a plasma cutter. I was thinking for the offset balance control called for Aluminum TIG welding. So not there yet and carefully paranoid to be safe before I do any hands on being the capacitors alone really small in size can pack a punch and be lethal potentially. Looking forward to using the Elements design and simulation app. Thanks for all again!
Great video! But unfortunately, i was not able to find out where i can find this Elements circuit simulator. It seems, that all components are already included in the library. Does anybody know where to get. Thanks!
yes you can , but put a diode in parallel with the motor to prevent the voltage spike from the inductance to damage the MOSFET (similar as I did for circuit #2 testing with the load)
Ahh so thats why you need to drive them, I only used a mosfet in a battery capacity tester that switched on and off once every few hours, I had no idea you'd need more voltage / current to switch them fast. I was going to say why cant you just drive them directly from the arduino, now i know, would have been interesting to see the performance anyhow. I coincidentaly salvaged some "logic level gate drive" mosfets today (D30NF06L) and was trying to make sense of of the difference before seeing this video.
Well it's a good practice to not use the signal directly from the microcontroller. The output mosfets of those little guys are not meant to drive more than a few milliamps (this is even worse with the most recent ones) and it's better to fry a cheap and easy to replace discrete component than having to deal with a fried pin (or a fried microcontroller). This also ensure your transistor is completely saturated and way outside of the linear range. And putting some darlington circuit with a small signal transistor driving a larger one allows better efficiency. Finally, BJTs are a good security measure even when driving low current since they gracefully go in safe failure instead of short circuit.
I like your presentation but may I suggest a 12v sorce as most, if not all, projects with the Ardunio and Rasberry PI are 9 to12 voll supplies and I want to learn how to control mosfets with those controllers. Thanks and I hope to see some examples... Rick
Thank you richaredneal384! The circuit works with 12V, I used 24V because it is commonly used for LED flextapes and to show it is suitable for higher voltages 🙂
Can you go in to the 25kHz - 300kHz range? With the ESP32’s LED PWM circuit it’s finally possible to have truly flicker-free dimming even at low brightnesses but it’s difficult to match the other components in order to make it happen.
Thank you for this very informative and practical circuit with critical analysis. I would like to know if inductive load can be triggered with high side switching. Here the MOSFET is used as Low Side Switching. Any idea? or can you kindly do a high side switching, meaning the source of MOSFET is connected to an inductive load and +24 feeds directly to the Drain of MOSFET. Thank you sho much for sharing your knowledge. I am a second year studen in Electric and Electronics Engineering.I am working on a higher frequency design, say from 45KHz to 2MHz. If there is a gate driver IC, please give some ideas of practical circuit. I searched couldn't find one except your video is very helpful and gives engineering details. Thank you so much.
.I am working on a video for high side drive of N-MOS which would work for you, but it may take a few weeks before I publish. This pdf from TI may be helpful for you. /slua887a.pdf?ts=1705275507968&ref_url=https%253A%252F%252Fwww.bing.com%252F
Hi Steven, these are circuits from my memory from the 90's, I just verified them by simulating and building them. I did not have practical experience with the 3d circuit (cascode), I heard of it before and found one reference here: electronics.stackexchange.com/questions/264142/drive-a-mosfet-via-bjt MOSFET driving is very specific knowledge, so it is not easy to find good reference information. You can check application notes of Texas Instruments, they have some great material like this pdf: www.ti.com/lit/ml/slua618a/slua618a.pdf?ts=1722369784772
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This is hands down the best circuit design and simulation video I’ve seen. Your ability to take us step by step through each circuit then compare the theory to practical application is amazing. I hope you continue to make videos like this. I’m still an old guy beginner in the EE and RF fields. I learned more in your 13 min video than from hours of videos trying to explain the same circuits. Thanks!!!
Thank you 🙂
This was absolutely brilliant! I really enjoyed your explaination on the push pull circuit, as well as the demonstration on the effects of the 220 pf capacitor on the BC557 base. Liked and Subscribed!
Thanks David!!!
@@smartpowerelectronics8779 It would have been interesting to see the effects of a corresponding 220pF capacitor in the first circuit. I wouldn't expect a great improvement because the mosfet input capacitance is still charging through a 1K resistor, giving a typical time constant around 2μs with an IRFZ44, but it is not an expensive addition and you would then be comparing the three circuits on a rather more equal footing.
@@smartpowerelectronics8779can you please explain, constant current with driving logic with transistor & MOSFET?
On the second two circuits there are some improvements you can make.
If you split the 2K resistor to make it two 1K in series and run a capacitor to the output of your gate driver stage, you can get the switching times to be a bit faster. Adding an inductor in series with the 2K will also work but inductors cost more. The reason this works is because it causes the current in the lower 1K to not start changing until after most of the switching action is over.
On your 3rd circuit a small schottky in place of the 1N4148 does two things for you. The 1N4148 has a recovery time so when the MOSFET is to be switched on, there is a brief delay before the upper NPN starts to do its thing. Also with the lower drop of a small schottky, the gate of the MOSFET is closer to ground.
Isn't the delay from the 1N4148 kind of the reason it's there? I'm not an expert but I think he says something like that at 9:55
@@bartios The reason for the 1N4148 is so that when the lower transistor is off, the upper one gets turned on. The delay in which is on really is a matter of his wording to explain the action. He is taking the voltage on the collector of the lower transistor as rising at some speed.
Thank you for your tip!
@@smartpowerelectronics8779 So, we are waiting for update video with tests ;)
BTW: Can you explain why you use BC transistor instead 2N?
sounds like you know what your talking about ! the science of fast switching is quite meticulous here ! can you recommend a good fast gate driver that i can just buy already made ? : )
I find this video surprisingly good, compared to all you see online ! To the point, accurate, useful... And I even learned something !
Thank you yxyk-fr! Happy to hear you liked it!
@@smartpowerelectronics8779 Well, now, you know what you have to do: more of these!
"compare to all you" ... Dude this is the best in the world.
I am an electronics designer, or at least I attempt to be smart in electronics which I have learned that I some times fail to be :-) I have to say that I realy likes your clean way of explaining things up to a level that I share your videos to other designers that I work with, where we like to share clever tricks with each other.
Thank you for your kind words 🙂Good to hear that!
I'm usually a fan of MOSFET driver ICs out of laziness, but this was really interesting
Thank you, Werner! Yes, as a hobbyist an IC is easier and less prone to mistakes. These circuits are actually used in mass production in very high volumes because IC's are -believe it or not-more expensive than this bunch of smd parts...
Excellent. Much appreciate the time and effort that went into making this video (and others). Concise, clear and absolutely fascinating - I have a degree in Electrical and Electronic Engineering from UCL in England, but still find this channel to be educational and insightful.
Thanks David!
ive just bought all the components needed to make your cascode circuit !! i couldnt resist !! to infinity and beyond ! : )
Yeah, that circuit is fun, even though you do not save many parts compared to the 3-transistor circuit.
@@smartpowerelectronics8779 yeah, its a nice little challenge for me ! and i chose the cascode circuit because you said its faster than light ! : P hehe. and sharp on/ off times is what im looking for !! the parts will arrive soon. and i have also bought the gate driver chip you suggested as well. i also had a new nano board arrive today ! so i can trigger the gate driver chip soon and also use my hall sensors now ! and this way i wont be over voltage'ing the gate ! good luck to me ! ha thanks !
I learned a lot in this video for my hobby. Thanks for your effort and posting. I personally liked the driver idea with the 555 as well. Thank you.
Than you Berhard! Electronics is a great hobby, started at 10 yours old with a flipflop blink light which I wanted for my electric train, now 56 made my job out of it, but still tinker around in my free time!
Very interesting & useful! I didn’t know about the base drive bypass cap pulling charges out of the b-e junction for faster turnoff before, thanks!
Or use a diode, schottky prefered, in reverse and parallel to the resistor in place of the cap. This video is cool, throughout, and clear. Thanks.
Amazing video for only 13min!
Simulation and real world example!
I would love to see #4 using dedicated gate driver.
Super thumbs-up! I especially like the summary chart where we can compare the three circuits side-by-side. Explain the 100 nf capacitor; what does SPICE show when the 100 nf capacitor is in/out of the circuit.
This is what I was looking for for a long time. Thank you so much!
thanks this is a great breakown. super useful. gone into my references and i have subscribed :)
the capacitor on the gate input was a new one for me.
thanks for these valuable practical electronic lessons, it was beneficial, please make more of such videos in which every circuit is validated with real test
That takes me back. Used Simetrix for many years. I think it was the very best simulator. Also used the cascode driver for switching PSU designs back in the mid 80’s and was still using it for motor PWM driving in the 2000’s. The only downside is the addition voltage drop of the diode. Maybe not a problem for home electronics but it was a problem in automotive design when high current draw could cause local ground shifts.
Another well presented video for us electronics learning & exploring enthusiasts. Thank you very much for making such a good video and sharing your knowledge ❤
Great topic for a video! I'll definitely mess around with a few of these drivers. I use PWM and PWM drivers in a lot of my projects
Finally I found it. It's helping me a lot . Thanks you ❤🎉🎉
#4 gate driver IC with logic input
Haha, no no, that is too easy...but for sure they will outperform these circuits 🙂
Excellent! I often have a 3.3V logic level and have difficulty driving a MOSFET with it.
For the third circuit I would connect a 12V Zener diode to the collector of the BC547 and cathode of the 1N4148 to GND. This would limit the voltage to around 12V.
The base of the upper transistor does not go above 12V and therefore neither does the emitter.
The upper transistor would also not become saturated and would therefore switch off more quickly.
But it is difficult to predict the current through the Zener diode.
I like your solution. The zener current is best predicted with a "if the current doesn't go elsewhere" sort of thinking. The current in the pull up resistor always has to go somewhere.
Also: If you use two resistors in series as the pull up and run a small capacitor from the mid point over to the emitter of the upper transistor, you can use a much higher value resistor for the upper one. You only need much base drive to the upper transistor when you are in the process of turning on the MOSFET. The small capacitor stops the base drive from decreasing right at the time you dealing with the miller effect.
Good tip, I expect that will work!
Very nice! Can you also make simillar video instruction for H-bridge drive?
after experimenting with first example i found params for better delay: resistor 2.2k -> 100, parallel (to 4.7 resistor) cap 1n. on delay - 200ns, off delay - 310ns. also tried with diode after 2.2k resistor, delays almost the same
Mosfet sürmek için harika bilgiler.
Fantastic video and discussion. Would be great to compare the discrete bipolar circuits to a dedicated MOSFET driver IC.
Or compared to a 555 in buffer mode
Great video! Thumbs up!👍
Great Video, Thank You!
Thanks so much, …do you have any video with P-MOS output system?
Very clear and understandable. Thank you.
Great! The simple circuit with the speedup cap would be interesting!
Thanks HansBaier! The speedup cap will help, but not too much because the the switch on of the MOSFET is sooo long ~2600ns, a few 100 ns does not help too much. :-)
Thank you for the clear and concise explanations. Great examples! Any recommendations for a non-inverting mosfet drive circuit?
Thank you JessieKropp!...well only one more Transistor at the input, but that causes extra delay. To prevent starup flash I choose a GPIO which has no other function and set it to high first thing in your setup(), works OK for ESP8266 and AVR arduino boards.
I’d add a weak pull-up on that GPIO pin too.
Thank you for your explaination. What is simulation software are you using?
It looks like Simplis
Yes, Simplis (Simetrix), free version up to 140 nodes. @@moukafaslouka4796
Oh, sweet university memories...😂
Thank you for this great video!
Folllow #3 with a totem-pole for even more current, up into the 10A range even. That’s better than most monolithic gate drivers, though there’s nothing stopping you from just putting a totem-pole (or ZXGD300_) after a monolithic gate driver.
Thx ScroganY. You are absolutely right, the totem pole will not add much delay and can further boost the gate current. By the way BC547/557's are not the best switching bjts, I was surprised how well they stood up to the task ;-)
Good analysis of an area of circuit design which is surprisingly difficult to optimize. The Miller capacitance also works against you and becomes a big issue with high voltage switching.
Yes, at higher voltages that is an additional reason to not even bother with the simple resistor pull up drive.
Also: "super junction" MOSFETs are much better for high voltage. Even with 1000V on the drain, the gate acts as though the drain only went up to about 200V.
For those who don't know: Internally a super junction MOSFET is a lot like a normal one but some P doped silicon extends further down into the bulk of the device. This P doped silicon looks like the gate of a great big JFET wired in cascode with the MOSFET. This spreads out the voltage gradient in the silicon making 1600V parts possible and also means that the full drain voltage happens at a place further from the gate.
Конечно лайк. Очень подробно и наглядно объяснили! 👍
Please share the simulator used by you. Really nice explanation with simulation.
Simetrix, free version. www.simetrix.co.uk/
Perfect explanation!!!! Thanks.
Thank you kostiapongo! Glad it was helpful!
BRILLIANT ! Thank you.
Thanks Tony!
Thanks for sharing and Happy New Year
Thank you Edmorbus! Happy new year!
Came up with that cascode cct for a commercial product back in 1981 and was rather pleased with it. Then a bit later I found it in a Philips publication that may have just predated it.
Really!? Cool I used "real" cascode in CFL's at the company you just mentioned: a low voltage MOSFET switching off the emitter of a power bipolar which has its base connected to 12V with a resistor.
Can the third gate driver circuit drive high side mosfet in half bridge configuration?
Just use a IRLZ44 it’s the upto 5v gate version.
I run it straight off of the arduino pin and common ground. It only uses voltage to se itch on or of so no issues with current.
There is always a little current required to overcome the gate capacitance, but charging and discharging a few picofarads directly from the Arduino is usually fine, I've done it to around 30kHz without issues.
@@TheLordNemesis the video is very interesting,and your use of the simulator is excellent thank you
In the Fast Push-Pull Circuit, are the push-pull transistors backward in their position?
Super! Thank you very much!
That cascode drive is smart but has big issues, especially when done in a pullup like this.
1. The output is high when no input is present, so your gate will be high until your MCU boots up. This can be fixed by connecting a pullup resistor to your gate driver input. Also that means it's inverted.
2. BJT's saturate and make high speed drive for dc-dc converters a pain. (high dead time, delay and all that)
3. The drive is non symmetrical, so you can have good turn off and bad turn on and vice versa.
I've played with these gate drives a lot and push-pull is my go-to for now if i want predictable timings ;)
On #2 part of the fun of electronics is working out how to make that not matter in the design.
Bài giảng rất tuyệt vời xin cảm ơn đã chia sẻ với khán giả
One comment on the schematics for rather figurative reasons hinting at an engineering necessity: the emitter of the lower BC547 should be drawn with a line directly to the source of the iRFZ44. The idea behind it: The electric connection should also be as short as possible to minimize ground spike effects.
Very nice solution though. Congrats!
Waw, merkwaardige resultaten! Schitterende video!
Dankjewel!
I also did not expect that the bas-cap would have so much impact, maybe it is because I use BC547's which are not really suitable for switching applications (but every hobbyist has some lying around...)
Gelukkig Nieuwjaar!
great video . pls what is the name of your simulator
@@derrickadusei7987 it is simetrix, simplis , the free version
why using 1% duty cycle? What will happen if w use 50% or more? Power losses will stay same? And will that going to allow us higher frequency (more 10Khz) to operate the first circuit?
I actually use 99% duty cycle, so the load is 99% of the time on in the simulation. 99% results in the maximum loss (conduction + switching loss)
For the first circuit the ELECTRICAL limit is the on/off time which is in the range of 2.5µsec, so you can go to 100kHz at 50% duty cycle, 5µsec on/off.
Thermally 100kHz at 50%is NOT ok because the switching losses will be too high. Hence 10kHz is the maximum.
@@smartpowerelectronics8779 Hi, thank you for the explanation, very helpful. One more question, is it possible to calculate the gate driver efficiency? And also can we use MOSFET instead of BJT in the level shifter?
Am I right with my guess that a bipolar transistor is used instead of a small mosfet like the BS170 because the driver transistor's switch time doesn't matter much compared to the power MOSFET's switch time?
Yep and because you probably already have a npn lying around 😊
@@smartpowerelectronics8779 You're right, I did! I also had the IRFZ44N, it was like magic.
Nice! The speedup cap is interesting. I wonder what the current and power on the io pin looks like.
Thank you! The IO should be ok, the 220pF causes a minor extra loss of 0.5*C*V^2*freq ~ about 30µW? There is another solution called "baker Clamp" with a Schottky Diode over b-c but I did not try that.
@@smartpowerelectronics8779 I have done Baker Clamp circuits. They do get rid of the storage delay but they don't help on the miller. Also just a schottky means that you now have the added capacitance of the schottky in the miller effect. Baker clamps end up complicated in real life.
Also if you have a TN0629-N3 in place of the lower NPN, you can save some parts.
Thanks a lot
Excuse me sir, what software are you using to simulate the designs?
Looks like Simplis from Simplis Technologies
Simetrix Free demo: www.simetrix.co.uk/
Very useful !
Thank you Gerardzi!
Please list what CAD software you're using?
Hello Edward, I use Simetrix, free version
Thanks for the video. What simulator are you using?
Simetrix Free demo: www.simetrix.co.uk/
hi, great tutorial. I apologize if this is very basic knowledge I'm missing, but why can't we directly connect the MCU's GPIO pin to the gate of the MOSFET? MOSFETs have insulated gates so they won't draw any (or perhaps very little) current, right? much less than the base of a bipolar transistor for sure; so why go through the trouble of connecting a separate NPN for example in the first circuit? Thanks.
Is the drive circuit what triggers the mosfet gate or what the mosfet powers/drives?
The drive circuit triggers the MOSFET Gate
Hello Mr T's. What is the simulator did you use to simulate in your video?
www.simetrix.co.uk/
the free demo 🙂
Stupid question: What would occur if we introduce a parallel capacitor to the resistor on the PWM signal line? In the second diagram, you've shown that the capacitor diminishes the switching delay, so couldn't we enhance the first diagram by including a basic capacitor? This would also ensure that the signal logic is consistent across all three diagrams...
When you do this with a logic signal from a micro, the edges on the micro's pin get slower while the driven circuit gets faster.
Your logic is right, The capacitor will speed up the 1st circuit too, but the switch on is sooooo slow that it would not make a big difference.
Nicely explained.
Thank you!
@@smartpowerelectronics8779 You are welcomed, always.
I am not very good at explaining ...
Thanks for the video.
Instead of using mosfet driver, how about the 74F or HC series IC? Thanks!
Great vid!
In the first circuit, the capacitor across the gate drive resistor would not make any difference ?
yes, but only a very, because most of the delay is caused by the resistor charging the gate slowly. The 2 delays add up.
Great video. Thanks
This circuit was used in old russian TVs to steer vertical deflection coils :)
Cool 🙂
Hi, good video, what is the circuit simulator ?
Simetrix Free demo: www.simetrix.co.uk/
One thing that can be done is to NOT shut-off the bipoar transistors totally. Keep them biased just a little and the charge time on the base will decrease. If you do so, the circuits can run easily 10x faster. I have made circuts with BC107 with respond time in nano second region by just letting them be biased instead of having the gate totally discharged.
Yes you are right, bipolar transistors can run really fast if they are not saturated, I mean, you can make FM transmitters at 100MHz with them! For power supplies, you do want to drive them in saturation to get as much current out of them as possible, this will slow down switch-off but it is still fast enough for the "low" switching frequencies of power supplies of 50-100kHz. So it is a trade off.
By the way I have good memories of BC107's in metal can, I used 2 to solder my first blinky-light as a kid, no idea how it worked, just followed the magazines' instructions but that was what sparked my interest in electronics 🙂
@@smartpowerelectronics8779 Thanks for your excellent videos. It wasn't intended as criticism on your video, it was purely intended for the viewers do go further in their own investigations.
so ive got my hall sensor triggering my arduino and then arduino into a gate driver chip and then gate driver chip into a mosfet.
but the coils are being turned on for wayy to long and its over heating the coils very quickly and not even getitng up to speed, very un smooth, i have a 100 ohms resistor between gate and driver output and10k across gate/source. and a 4k7 ohm reisstor between arduino out and gate driver logic input. can you suggest what im doing wrong here ??
Nice video and thanks for uploading.
Just one question though. You say these circuits invert the logic signal.... but...
If the input voltage is high with respects 0V then the MOSFET is off and the output voltage is high with respects to 0V too.
Doesn't that mean the circuit Does not invert the signal? (In terms of Voltage)
The signal driving the mosfet gate is inverted with respect to the MCU signal driving the first transistor. Of course, the mosfet will also invert the signal applied to its gate, which means its drain will go high when the input from the MCU goes high. The two stages together indeed do not invert the signal.
It's hopefully obvious, though, that the drain is high when the mosfet is off, and therefore no current passes through the load.
Hello, thanks for your video
can you explain the choice of the BJTs for this push pull, I am trying with BJTs that have Ic=10A and I can't get a good signal at the output.
2SCR582D3 for the NPN and 2SAR582D3 for the pnp.
Thanks
Do you have anything on driving a high side mosfet without resorting to having to use a p channel mosfet? I came up with one circuit, but it involves an extra 12 volts added on to the supply voltage, and having the transistors running at those high voltages.
If you want to drive the N channel, you are going to need those higher voltages. They do make chips that contain charge pumps for doing just that but if you want to go with common parts, there are tricks.
If the switch is being driven with a duty cycle, you have a squarewave somewhere to drive a charge pump.
Thanks, a great lesson! What program do you use to model circuits?
It is probably the MPLAB Mindi Analog Simulator program from Microchip. A free version of this program exists, but it has limited capabilities.
@@GluonToo Thank You
How much voltage the mosfet will be able to deliver at 1% duty cycle at 10khz can ve able to detect that voltage or not.
The 555 can work as a buffer for driving a MOSFET too.
The only downside is that if the Arduino locks up, the 555 might lock on too
Yes but if you have the 555 you don't need the arduino do you.
@@kensmith5694 depends if it's a standalone function or if this mosfet is part of a more complex project.
@@PainterVierax My comment was intended largely in humor. The idea is that fans of the 555 will tell you that you can do anything with it. There are a really large number of things that I have done with a 555 including a radio transmitter and stuff like that.
@@kensmith5694 yeah 555 fans are excessive. The IC is very versatile but it has severe limitations as well and it's not that easy to configure.
It does the job but rarely worth it as a square or PWM emitter nowadays.
Hey that might work, and it will make the 555 fans very happy.it is worth a try! 🙂
Very interesting explanation. Can you please tell me what your simulator is and where I can obtain one. Thank You!
simetrix, free version, max 140 nodes.
www.simetrix.co.uk/
There are also real free simulators like LTSpice, but I happen to be a little familiar with this one.
@@smartpowerelectronics8779 Thank You!
I tried it. A great tool. Thanks again!
Nice circuits! My only concern is that these are all negative true, so when power is first applied and the Arduino hasn't yet fully booted, there may be a momentary period where the output is on. Any thoughts on how to prevent that?
You are right, so you need to check the starting conditions. You can also add a pull up resistor to the base of the transistor connected to the arduino to make sure it is high at startup.
Great video! Thanks for all the detail. I was looking again at electronics design to repair some modules I invested in to charge my Prius HV batteries if needed from sitting to long. Possibly use as a battery tender as well. Anyways, this got me thinking some more about control of the H bridge of the other gen 2 and gen 3 inverter converter assemblies I got from the salvage yards since I couldn't believe they were so cheap, like $20 for some of them at one time when the 50% off sale and even then about $75US then at most before half priced. The gen 2 inverter converter assembly is more modularized and seems based on the specs can more easily make a universal pure since wave inverter for whatever rectified generator inputs within spec input range. Plus have the three phase option. Seems can also be controlled to make a multifunction welder and maybe also a plasma cutter. I was thinking for the offset balance control called for Aluminum TIG welding. So not there yet and carefully paranoid to be safe before I do any hands on being the capacitors alone really small in size can pack a punch and be lethal potentially. Looking forward to using the Elements design and simulation app. Thanks for all again!
Great video! But unfortunately, i was not able to find out where i can find this Elements circuit simulator. It seems, that all components are already included in the library. Does anybody know where to get. Thanks!
www.simetrix.co.uk/
you can use the free demo version, it works "up to 140 nodes"
is it possible to use this mosfet to drive a motor (because of inductance) ?
yes you can , but put a diode in parallel with the motor to prevent the voltage spike from the inductance to damage the MOSFET (similar as I did for circuit #2 testing with the load)
What is your Simulator called? Elements ...
Good explanation of all the options. Thanks
Is it mandatory using bjt pushpull for high switching like 200kHz?
Yes, for 200kHz I would add the push-pulls
@@smartpowerelectronics8779 Thanks for replying
very nice video .
Ahh so thats why you need to drive them, I only used a mosfet in a battery capacity tester that switched on and off once every few hours, I had no idea you'd need more voltage / current to switch them fast. I was going to say why cant you just drive them directly from the arduino, now i know, would have been interesting to see the performance anyhow. I coincidentaly salvaged some "logic level gate drive" mosfets today (D30NF06L) and was trying to make sense of of the difference before seeing this video.
Well it's a good practice to not use the signal directly from the microcontroller. The output mosfets of those little guys are not meant to drive more than a few milliamps (this is even worse with the most recent ones) and it's better to fry a cheap and easy to replace discrete component than having to deal with a fried pin (or a fried microcontroller).
This also ensure your transistor is completely saturated and way outside of the linear range. And putting some darlington circuit with a small signal transistor driving a larger one allows better efficiency.
Finally, BJTs are a good security measure even when driving low current since they gracefully go in safe failure instead of short circuit.
Can i change the IRFZ44 for a PNP Mosfet ? making it PNP normaly open, and switch highsize ? or does the circuit need modification ?
No, a PMOS will not work you will need another circuit for it. I have another video that shows how to switch an NMOS at the high side though.
I like your presentation but may I suggest a 12v sorce as most, if not all, projects with the Ardunio and Rasberry PI are 9 to12 voll supplies and I want to learn how to control mosfets with those controllers. Thanks and I hope to see some examples... Rick
Thank you richaredneal384! The circuit works with 12V, I used 24V because it is commonly used for LED flextapes and to show it is suitable for higher voltages 🙂
Thanks
Can You make the same for p-mosfet?
that's almost the same circuits. Try to experiment within a simulator to find the behavior you're looking for.
Have you ever tried LTspice to simulate circuits?
Can you go in to the 25kHz - 300kHz range? With the ESP32’s LED PWM circuit it’s finally possible to have truly flicker-free dimming even at low brightnesses but it’s difficult to match the other components in order to make it happen.
Very good video for me.
What is the software that you use to analyze your circuits?
Thank you for this very informative and practical circuit with critical analysis. I would like to know if inductive load can be triggered with high side switching. Here the MOSFET is used as Low Side Switching. Any idea? or can you kindly do a high side switching, meaning the source of MOSFET is connected to an inductive load and +24 feeds directly to the Drain of MOSFET. Thank you sho much for sharing your knowledge. I am a second year studen in Electric and Electronics Engineering.I am working on a higher frequency design, say from 45KHz to 2MHz. If there is a gate driver IC, please give some ideas of practical circuit. I searched couldn't find one except your video is very helpful and gives engineering details. Thank you so much.
.I am working on a video for high side drive of N-MOS which would work for you, but it may take a few weeks before I publish. This pdf from TI may be helpful for you. /slua887a.pdf?ts=1705275507968&ref_url=https%253A%252F%252Fwww.bing.com%252F
PS some examples of resistor calculations would be great.
pls tell me what software you use for shematic.
Simplis from Simplis Technologies.
@@stevem1097 thank you very much
KiCAD 7 for the schematic: www.kicad.org/ (free)
SimeTrix for the simulation (www.simetrix.co.uk/ I use the free version)
@@smartpowerelectronics8779 thanks
BRAVO !
Thank you 🙂
Can the third circuit run at a voltage of 3v - 8.4v with a battery as a voltage source
No it can not, the IR2104 locks out below 8 Volt.
You can search for another lower voltage IC
@@smartpowerelectronics8779What I mean is cascode drive, not ir2104
Could you please share the source where these circuits appear?
Hi Steven, these are circuits from my memory from the 90's, I just verified them by simulating and building them. I did not have practical experience with the 3d circuit (cascode), I heard of it before and found one reference here: electronics.stackexchange.com/questions/264142/drive-a-mosfet-via-bjt
MOSFET driving is very specific knowledge, so it is not easy to find good reference information. You can check application notes of Texas Instruments, they have some great material like this pdf: www.ti.com/lit/ml/slua618a/slua618a.pdf?ts=1722369784772
Excellent, but you keep switching between left and right shoulder makes newby headache.