P-channel MOSFET as a High side switch | Why is it hard to use N-channel MOSFET as high side switch?

[@aduedc]

Hi, I am a chip designer, and I love your clips, because it teaches me how to do many things at the PCB level. In the chip level, we use either a capacitor or butterfly circuit to do this. In capacitor method as you know, we connect the capacitor to ground and Vsup through two switches, then when we want o turn on the high side NMOS switch we We turn the capacitor switches off and connect the ground of capacitor to supply and the other side of the cap to the gate. The gate of NMOS will fly to twice the supply voltage which turn of the NMOS. However, doing this in chip level is easy because the transistors are almost free, but at the PCB level we need four transistors to do that and becoming familiar with the chips that are already available is a blessing and better way to do that. This is why your clips are so interesting to me. Thanks for the good work.

[@FoolishEngineer]

Thank you so much for watching!! Please don't forget to subscribe to our channel

[@TheAnbyrley]

I'm becoming curious about the difference between the two design philosophies. Do you have any references for the chip level design? I'm a DSP engineer but like to play around with PCBs.

[@chimeranzl9147]

as a beginner in electronics, i spent ages trying to read and understand this concept. thanks for making sense of it - you explanations backed up with examples makes it so much easier to conceptualise!

[@FoolishEngineer]

Glad it was helpful! Thank you so much for watching!! Please don't forget to subscribe to our channel

[@chimeranzl9147]

@@FoolishEngineer how do I use a P channel MOSFET as a high side switch if the gate voltage is from an ESP8266 (3.3V) yet the load (via drain) is 24V? I can never get that voltage differential to turn the MOSFET on? I can't use a N channel MOSFET here as the load has 3 x positive inputs and a common ground.

[@emjaycpe]

By far the best video about mosfet switching on KZbin. Great job!

[@FoolishEngineer]

Thank you so much! Please show support to my video with Super thanks.

[@Alex-xl4xe]

I'll be honest, the accent is a bit difficult for a non-native speaker but you are trying incredibly hard to make it work and that's noticeable, the video quality is top-notch, everything is explained very well and understanble.

[@FoolishEngineer]

Thank you so much! Please show support to my video with Super thanks and don't forget to subscribe to my channel

[@Leif_YT]

Thank you for this very useful content. I really like that you separate it in multiple videos. This way it's very detailed and at the same time easy to find what someone is looking for. Great work

[@FoolishEngineer]

Glad it was helpful! Thank you so much for watching!! Please don't forget to subscribe to our channel

[@kabuchi254]

Your are a Smart Engineer. Getting to learn more that I didnt know from you.

[@FoolishEngineer]

Thank you so much! Please show support to my video with Super thanks.

[@neilnerd8111]

Thanks for a clear description of biasing a p channel MOSFET!

[@mekh3317]

thank u for this vid. It really helped me understanding the function of different mosfets and selecting the right mosfet for a power source selection switch.

[@FoolishEngineer]

You are welcome!

[@palliyil]

Looks like your channel has become a MOSFET dedicated channel now :p But that is a good thing probably. All the relevant information needed in one place. Your videos are at a digestible level for someone who knows some hobby electronics. And I really like that you do not try to pack too much in a single video. Ideal for use in teaching. Wherever someone asks me something related to mosfets i just redirect them to some of your videos. Keep up the great work!

[@FoolishEngineer]

Thank you so much for watching!! Please don't forget to subscribe to our channel

[@james-sargent]

you ahve finally made sense of the -V values in p-channel data sheets, I cannot thank you enough :p

[@FoolishEngineer]

No worries!

[@Ed19601]

With a P-FET, switching on the FET is usually not a problem....just switch your driver pin LOW. However, switching it off may be a problem. Sure, if your driver pin is equal to the voltage on the Source, it will switch off, but most output pins of say a microcontroller, will not reach Vcc but stay slightly below it. If your MOSFET has a LOW Vgstreshhold tat might be enough to slightly open it. If one picks a MOSFET with a Higher VGS(th) that should not be a problem....but then say a 3V3 system may not be able to fully open the P-FET

[@NOW-IS]

Would defining an MCU output to an input with pull-up solve the issue of completely switch it off? I have a strange phenomenon on my circuit where I want to switch on external logic chip and off again. Sometimes it seems that the chip is not really in the same initial state and lost somewhere in nirvana and does not respond. I think it could be related to what you explain. So may this be a fix or do I still have a difference between gate and source?

[@Ed19601]

@@NOW-IS interesting thought but in fact you are saying: let's try to get a higher voltage fed to the MCU pin. No real problem if the issue is that your mcu pin stays just below the rail voltage, but maybe not something that would work on a shared 3v3 / 5V system. Definitely worth a thought though

[@kissmyaxe9121]

Could be easily solved by adding a pull up resistor of let's say 10k and connect it to vcc

[@SubwayJack919]

Concise explanations with excellent visual's!

[@FoolishEngineer]

Thank you so much! Please show support to my video with Super thanks.

[@rayoflight62]

You could have emphasized the comparison with a bipolar transistor. When the switch is connected with a common source configuration, the MOSFET works an an amplifier. When the MOSFET is connected in a common drain configuration, it acts as a voltage follower, with unity gain...

[@ramagirikuna1586]

Hiii sir am currently working as design engineer..,Really your classes are worthble...❤

[@FoolishEngineer]

Great 👍

[@ahmedbadr328]

What a great explaination But i have a question, if i use high voltge Vsd (about 50V) so that means if i want to turn off the MOSFET switch, i should provide Vdd very high so that voltage difference between Vgs not exceed -4 V (suppose that is Vthreshold) right?

[@LRoy-pp1uo]

Hello, I like your videos, I want to learn that, what is the advantage of high-side drive over low-side drive, when is it better to choose high-side drive, and also what is the effect of them on the efficiency of the circuit(which has higher efficiency)?

[@BoxingDayAC]

In reverse polarity protection, low-side has two problems that high-side does not. First problem is creating a voltage across the transistor's Rds on the ground itself. Second problem is separating the ground between the power source and circuit. In practice, this voltage is very small and probably within the acceptable noise level in most circuits. Splitting the ground should be fine in a battery-powered circuit but bad practice in a circuit powered from an outlet. High-side problem is just higher voltage loss from PMOS having higher Rds than NMOS. Thus PMOS is less efficient. Can use NMOS in high-side with a charge pump but that adds cost and complexity. One option for the charge pump meant for reverse polarity protection is the LM74610. Also, the zener + resistor aren't needed if you'll never exceed the MOSFET's Vgs limit, which is fair to say, never going to happen in a 3V battery circuit. Is a risk leaving them out in a circuit powered from the outlet due to voltage transients.

[@riaank.4585]

Thank you very much! I don't see yet, how you could switch OFF the P-MOSFET , i.e. how you could change the positive gate-voltage from VDD to 12V-MOSFET-supply...? Is an internal BIP-Transistor used for that inside the MOSFET-driver?

[@hichamtassi1753]

Good day Sir, on a H Bridge of power inverter, i have always mosfet 1 (high side) and mosfet 2 (low side) that burn while 4 and 3 stay ok. Please note that they burn ONLY WHEN I TURN IT OFF, when ON, all is good. When i use only 3 mosfets, none burns (1,2,3 or 2,3,4). I checked on the scope, signals are identical and voltage between gate and source are the same for low and high side. I am running out of mosfets and i would like to fix that inverter, any idea where to look at ? Thanks.

[@errayyanar]

In motor driver circuits, we use N-channel MOSFET as Low & High side MOSFET, Why we are not using P-Channel as high side MOSFET in that case ? I suspect reason is, 1. Rds(on) high in P-Channel 2. To turn on & turn off high side MOSFET at same speed as Low side MOSFET to have synchronisation in on & off ? Any other reason or wrong assumption? Kindly reply.

[@sabriahmed8203]

Nice job keep on.how can drive two mosfets N channel and p channel in same time with a sine wave with a high speed.

[@RGDitchon]

Romeo Jr. Thank you for the P Channel and N Channel relevant info Just ask about the resistor at the Gate how many ohms is it thanks

[@FoolishEngineer]

You can refer my other video to calculate the appropriate gate resistor value

[@luisfreire5724]

gracias x el video y por los subtitulos en ingles ....ayuda mucho

[@FoolishEngineer]

¡Muchas gracias por mirar! Por favor no olvides suscribirte a nuestro canal

[@TheArmaanuiet]

Hi, i need help, to make a mosfet as switch, The source supply is 28 volts and load is 7 Ohm. Hence around 4 amps of current will flow. This entire circuit to be controlled by a 3.3 V control signal. Kindly suggest a logic level driver along with a mosfet.

[@petername2608]

Can you make 6 series MOSFET switching circuit using gdt

[@tomazis100]

Hi , so how can we switch a higher voltage like 60V with a N-channel fet ;

[@koldenrjk]

P channels @ over 60 amps are becomming scarce - I need to switch to n channel perhaps.

[@jameswyatt1304]

As you scale up, the P-channel refers to "parallel", LOL. Spreading the load between multiple FETs also allows better spread across a heatsink.

[@TheSlagor]

I did not understand + 7volt. or - 7volt. on the gate of p-mosfet ?

[@TheArmaanuiet]

+7 volt, as voltage at gate minus voltage of source would be -5 voltage, negative allowable vgs will turn on the mosfet

[@Dc_tech386]

That’s why I see 129volt on the gate of the mosfets on my fully bridge driver because the gate and the switching voltage have to be almost the same to fully switch high side on that’s one information never mention in any mosfet data sheet so why is this information hidden from the user on the product

[@HemendraSinghChouhan-po2pp]

Sir for irf840 N channel MOSFET can we use ir2113

[@prashantmirjapur4772]

is there additional driver circuit in buck converter as they use nmos high side switching ? If yes then why they don't use pmos instead that complex circuit

[@edisont.picard4112]

Usually a charge pump gate drive is used to switch the nmos. The reason why is that pmos is more expensive than nmos and it is much less .efficient. The Rdson of nmos is much lower than pmos, therefore less energy will be lost as heat during switching. This is important in portable battery powered applications.

[@happyatheists9361]

thanx...love from_Sri lanka

[@FoolishEngineer]

Thank you so much for watching!! Please don't forget to subscribe to our channel. Take care

[@mery.m]

at 2:29 Is the Vdd power connected to the 12 Volt battery and if so why is it allowed. isnt it a short circuit? I`d be glad for any answer

[@edisont.picard4112]

Why would it be a short? Vdd is the driver positive power supply input. It doesn't have to be the same supply as the load, but it usually is.

[@tyronearendse1722]

Hi friend thanks for another informative video

[@FoolishEngineer]

Thank you so much for watching!! Please don't forget to subscribe to our channel

[@tyronearendse1722]

@@FoolishEngineer I am a subscriber already, your explanations makes easier to understand, thanks again

[@jugaatbaat8891]

Can this circuit also be used for IGBT's ? do help me out please.

[@FoolishEngineer]

Yes

[@Patyx42]

Thank you so much!

[@FoolishEngineer]

You're welcome!

[@priteshkchoughule5748]

Great information

[@rameshwarshelke4633]

Thank you sir .

[@FoolishEngineer]

Thank you so much for watching!! Please don't forget to subscribe to our channel

[@kaiserschnitselsr]

voeltaasshh?

[@vijayanand7952]

Thank you

[@FoolishEngineer]

Thank you so much for watching!! Please don't forget to subscribe to our channel

[@flashuma]

Thanks

[@FoolishEngineer]

Thank you so much for your super thanks!!

[@kimienick6721]

Lol I always confuse with spelling OMPH cause to much see words UPM lol 🤣🤣🤣🤣🤣... 16V using for push your starter more powerful and food for music sound effects... BTW sorry for saying this lol it's old school skill now we have APP electric system

[@jenkinssthomson8879]

Poor choice in using 7 v bc it’s not a realistic or practical real world example

[@josepeixoto3384]

that is why i wonder how some youtubers are really good common world techs

[@NICKLASFARFAR]

It makes perfect sense as it illustrates the maximum voltage that would turn on the P-fet. He even mentions grounding it afterwards as the realistic use case, thus connecting it to 0 volts and getting -12v VGS instead of the -5V VGS he got when he mentioned a 7V connection at the gate pin.

[@herobrine1847]

Here the engineer goes on again about “real world examples” 😏

[@arashcrouse2]

Thank you