MOSFETs: High-Side vs Low-Side Switching

Рет қаралды 89,629

Jonathan Currie

9 жыл бұрын

Describes why N-Channel devices are typically used in a low-side switching configuration.

Пікірлер: 72

@Derrekito 8 жыл бұрын

Thank you, thank you! You managed to put the difference between high side and low side switches into a context other resources lack. I sincerely hope you continue to publish tutorials.

@klab3929 7 ай бұрын

It's pretty insane a 8 year old video helps me now in 2023 almost 2024!

@marckman1411 3 ай бұрын

No it's not these electronics are old

@MrBomer213 3 жыл бұрын

thank you so much for your video, I learned this in school but just memorized a lot to pass the class rather than understand. I am now working in the field and I was ashamed for not understanding it, after this video I understand completely

@joetotalejoe 8 жыл бұрын

Thanks for this, JC. Really clear explanation of the principles that has helped me understand this so much better.

@alpha2assassin 5 жыл бұрын

So far the best explaination that I came across for high/low side driver on KZfaq :) Thanks alot Jonathan Currie!

@abhisekrout8522 4 жыл бұрын

Thank You so so Much. I have been using Low Side Switching all the time and never gave much thought into high side switching. Thanks again for bringing into me that different perspective.

@ismetcelik6770 3 жыл бұрын

Mr. Jonathan, you are the only human that tell this issue clearly and easily I have ever seen in the world.!!!!!

@raghavab821 Жыл бұрын

I agree he is awesome

@AlgorithmicChaos 3 жыл бұрын

Thank you so much. This was exactly the kind of explanation I was looking for

@youpattube1 Жыл бұрын

I ran into the issue of high side switching with an N channel requiring an increased gate voltage. While I had a sense of why this was happening, I was just guessing. You sorted it out nicely. So nicely in fact that I am aggravated at myself for not figuring it out. Nice explanation. Thanks for the video. Now I'm hoping that you have a video that just as clearly explains how to use a P channel in a high side switching configuration.

@agstechnicalsupport Жыл бұрын

High-side and low-side switching very well explained. Thank you for sharing !

@jboard146 5 жыл бұрын

Very good explanation. Thank you!

@chiranjeevilokesh7572 3 жыл бұрын

Good one.. Love to see more videos on electronics

@shadmehraria5473 Жыл бұрын

Well and clear explained, Thanks❤️

@deepu3100 2 жыл бұрын

Understood 200%... Thank u so much

@CrazyRupes 3 жыл бұрын

Awesome explanation :) thankyou.

@deepuv7 8 жыл бұрын

Great explanation.

@wuxiuchengwang180 7 жыл бұрын

Thank you! Very helpful

@tshilidzifunyufunyu51 6 жыл бұрын

This is beautiful thanks

@mandelbro777 4 жыл бұрын

great explanation ... web needs more people talking basics.

@srinivasraor770 5 жыл бұрын

really good video and useful information's too

@PwrElec 7 жыл бұрын

Nice job!

@psionicxxx 4 жыл бұрын

As clear as a mountain lake :) Great !

@goshiluvarchie 7 жыл бұрын

thank you! very clear!

@HellaFunnyShorts 7 жыл бұрын

very well explained

@robertcumpacondori3453 7 жыл бұрын

Muchas gracias (thank you very much)!!!

@pradeepvenugopal5100 5 жыл бұрын

Super explanation Sir

@biteshtiwari 6 жыл бұрын

Thanks for the video

@dabdoube92 2 жыл бұрын

Simple. Effective. Thanks (:

@Vayumitra 5 жыл бұрын

Thank you so much 😊😊

@wisnueepis3593 2 жыл бұрын

thankyou this is answer my question

@user-jr6zs2nx7z 7 жыл бұрын

thank you!! sencerely

@faidularcs 6 жыл бұрын

Nice explain Thankyou

@lvmrevolutiondotinfo6421 Жыл бұрын

Great video, very informative. Now I wanted to ask if in the high side mode it is possible to put some inductance and/or capacitor to increase the voltage or recover the 3 volts lost.

@AparajitRituparna 5 жыл бұрын

Thank you

@manavshetty4449 3 жыл бұрын

Brilliant

@snnwstt 6 жыл бұрын

Someone can use a P-Channel on the High Side to be able to EASILY switch the transistor ON and OFF, instead of using a N-Channel. N-Channel is good for the low-side, but not so for the high side. And there are case where you simply cannot chose the side of the switch, as in the case of a motor, where you need to switch which motor's winding will be activated and which winding will evacuate the current: you need and a high side and a low side switch (H-Bridge).

@efivip93 5 жыл бұрын

You can use bootstrap with N-channel mosfet, and use it on the high side, without problem. The reason we want N-channel on high side, is because it has lower Rds(on), about 1/3, meaning less heat, more efficiency. Even on inverting circuit for 3 phase motor, I highly recommend N-channel.

@therealb888 2 жыл бұрын

@@efivip93 Hi, could you please explain what you mean by use "bootstrap with N-channel mosfet"? Also, why N-channel has lower Rds on & 3x more efficient than P channel? Does it have anything to do with the structure of the MOSFET & that the gate is doped N type semiconductor having more electrons? Lastly, the video called the MOSFET as a "device". Are MOSFETs "components or devices?" I assumed components are individual circuit elements like resistors, capacitors, diodes, etc while "devices" are packaged assemblies or ICs of these "components" like power controllers & converters, etc. Basically, what's the difference between "components & devices"?

@isacdaimary9908 Жыл бұрын

@@efivip93 Can you please explain what is Bootstrap circuit is all about. Thank you

@efivip93 Жыл бұрын

@@isacdaimary9908 In simple terms it is as follows. The gate-source voltage needs to be above a certain threshold to begin conducting and the higher you go the less the rds-on is, bellow a limit ofcourse. But if you use an N-channel mosfet on high side in a 36volt system as an example, then you can't supply the gate with more than that, so you can't turn it on. A bootstrap circuit is basically made of a diode and a capacitor that charges up when the mosfet is off and is abble to provide the required gate-source voltage to turn on fully and have really low rds-on. A lot of mosfet driver chips are supporting this, many allready have the diode built into the ic, so you only need to add the capacitor, you can find all the information in their datasheets. There are limits to this methood. Most of the time you are using it in pwm circuit, where you are not using 100% duty cycle, since you need a tiny bit of time to charge up the capacitor. Some manufaturers offer gate drivers that support 100% duty cycle, but it's not verry wide spred, again, read the datasheets about it. Hope it clears up a bit, if not, let me know.

@isacdaimary9908 Жыл бұрын

@@efivip93 Thank you for taking time to reply. Can you please design a bootstrap circuit for IRF840 MOSFET...Am stucked in designing a buck-boost converter where am unable to switch the MOSFET,,,,I used TLP250 as driver.

@waterfuel 7 ай бұрын

Seems likely I can still use Vcc 12v and reduce with voltage divider for use with N channel Mosfet and load, as HIGH SIDE SWITCHING. My test load is a coil, which in formula does not use voltage, only current , inductance and fast time in seconds. Circuit can use 9v or less to operate with Gate drive from 12volts DC. The N type has a lower "on" ohms resistance. P type can be used with it's higher ohms, as long as the current is very low, for lower waste energy heat. On the other side, the resistors of the voltage divider will waste energy , since they have to be of lower ohms for average amps needed. The P channel is probably better to use overall, for high side switching.

@WereReallyRelayCamping 5 жыл бұрын

hang on i must have missed a page, high side switching , when the mosfet is ''off'' then source is at 0v via the 1k, so only needs 3v on the gate to turn it on, then the voltage at S rises but it should stay turned on? wont the G then be below and cause the mosfet to then ''switch off'' and we have a resulting oscillation ?

@Dc_tech386 4 жыл бұрын

From how i look at it npn cant use in stable circuit in high side configuration so but to use npn for low and pnp for high

@dvignesh5 6 жыл бұрын

Im currently using Irf3205 n-channel mosfet and ir2110 MOSFET driver for Bldc Motor control using Arduino. MOSFET is not completely turning on by the MOSFET driver IC ?

@srinivasraor770 5 жыл бұрын

please check the data sheet of the mosfet your using and measure the gate voltage provided by the driver mosfets ,

@davidprice2861 5 жыл бұрын

Agree with all that re 'N' type, but with 'P' type I seem to need a slightly higher voltage on gate to fully switch. I'm trying to work out why ??? (yes p mosfet is on low side))?? Maybe I have bad mosfets..??

@robertodemarco6496 3 жыл бұрын

💯

@Schlezinger_Group_IL 10 ай бұрын

my dear friend! this is the first timr you mack me understand why I always conacted the load to the line(hot side), than swched to the (N) : now I realis the low voltag on the swich and the low current please help me with the half gate driver, how this is working with two MOSFET's on the HIGH side whan the LOAD is bittwin them?(FAN7382 or L6384E) MANY THANKS

@SubwayJack919 Жыл бұрын

On the highside MOSFET (on the right) isn't the source supposed to be facing up and connected to power and the drain connected to the loads +? I'm new to this so I'm asking because I'm not sure. I've seen other places saying essentially the left example is an N channel MOSFET and the right one would be a P-Channel MOSFET. But the way this is drawn makes this a high side N-Channel MOSFET which I though they couldn't do and hence why they have P-Channels. Again, I'm new. I might be missing lot of things. Thanks in advance!

@RainLovesCobain Жыл бұрын

yes, both switching devices here are N-channel MOSFETs and it is indeed possible to use an N-channel MOSFET as a high side switch

@H2ON_MEA Жыл бұрын

Thank you for sharing. Please I want to replace a relay in my car with a Mosfet . Notes : Every electrical object are connected to the ground . The switches and relays are delivered +12v to them. Asper you video I understand that the mosfet is open the ground to load. Can you please help. Thanks...

@Enigma758 4 жыл бұрын

What's confusing me here is that I have always understood that to turn on a PNP transistor the base must be lower than the emitter but in your case 14v > 12v which seems the opposite of that.

@simonO712 Жыл бұрын

I know it's been a couple of year, but just in case you're still wondering: these are N-channel MOSFETs, not PNP transistors. The MOSFET analogy to a PNP transistor would be a P-channel MOSFET.

@Enigma758 Жыл бұрын

@@simonO712 Correct, I had meant to say P-channel, not "PNP". Until you mentioned it, I didn't realize he was using N-channel for a high side switch. I now understand that that is not uncommon with mosfets (i.e. high side switching via N-channel - due to lower cost and lower Rds) and that is the purpose of a "bootstrap" circuit. Thanks for your reply!

@SourabhGachli 2 жыл бұрын

how would you drive n channel MOSFET at high side of circuit without using drivers?

@samet107 3 жыл бұрын

thanks for the explanation. Does it matter if the mosfet is a p channel or an n channel type? I bought logic level n channel mosfets the irlz 34 and 44n, to be specific and want to control a 5volt lcd on the high side with and arduino which can output 3.3v to the gate. It seems that it doesnt work as planned until i use the low side switch configuration. But i need to control the high side. Is there an efficient way to do it?

@3deeguy 3 жыл бұрын

One option is bootstrapping an N channel mosfet. The RDS-on for an N channel is generally lower than that for a P channel mosfet. That means the N channel runs cooler.

@psanath3348 2 жыл бұрын

So, Why can't we use p channel mosfet for high side switching.

@abhishekkole6465 5 жыл бұрын

Add for p channel mosfet please

@SurvivalSquirrel 5 жыл бұрын

Now where do i get my 14.9Volts from?

@AparajitRituparna 5 жыл бұрын

bootstrap / mosfet driver

@BubstechDOTcom Жыл бұрын

For what in my mind is a simple thing 3 mosfet I failed to work i dont know why even ready made mosfet boards were the signal ground goes in on pins and seprete power supply added ans 2 other connectors ÷ - i can't get it to flash a bulb 12v car light bulb my frequency genorator flashes the LED on the board i play with 3 nobs first rase lower the power still nothing im having bad luck i want to pulse a tesla bifoler coil i did not want to learn maths why can't it be simple as I think also you just showed me one thing I think low side switch is below the mosfet near ground but low is above mosfet near positive weard visa verser I want to play with one so then I can do 2 in serial with high turn one low turn the other to get positive and negative pulse it feels frustrating i classed my self ok with electrics but this prove im still dumb ass

@davidjackson2115 2 жыл бұрын

Good. Given pnp mosfets are crap and npn ones are good efficiency wise - why do they insist on diagrams such as buck converters with the mosfet on the high side, truly annoying is an understatement.

@DesertVox Жыл бұрын

This does NOT make sense. This should NOT be the case. This part of electronics is very much against logic and natural laws.

@Magneticitist Жыл бұрын

It's confusing because in both *cases the mosfet is going to pass threshold whenever the gate-source voltage passes the threshold. This is irrespective of VCC. The high side switching arrangement may have one think if a mosfet has a 4v threshold then they will need well beyond that just to slightly turn it on.