Confused about Logic Level Mosfets

Everywhere you read and see projects with IRL44N (logic level mosfet)
here where I live its's really difficult to get those, or expensive or even fake ones.
So today I did some experiments with a Nano and an ESP32 on breadboard, (see picture) I used an IRFZ44n and a K3053 everything works fine, even PWM.
So why I have to use Logic Level Mosfets??
I hope someone can light me up. :slight_smile:

Thanks and greetings from Java.

To light an LED, you don't. For a motor or something that requires a lot of current, you do. What sort of LED is D3 and where is the current limiting resistor?

This graph from the IRFZ44 data sheet shows the typical current flow at various gate voltages. Note that gate voltage 3.3V is not represented.

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MOSFETs which are not logic level will not be fully switched on by only 3.3V. They will only be partly switched on. Like this, their resistance will be higher which means their voltage drop and power dissipation will be higher. This can mean there is not enough voltage for the load, and the MOSFET can burn.

If the load is small, they will work. But for higher loads like pumps or motors, they might not work or they might burn.

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The gate threshold voltage Vgs(th), for an IRFZ44N can be anywhere between 2V and 4V. What that means is that if you buy 2 MOSFETs, one could have a Vgs(th) of 2V an the other 4V.
3.3V will never turn on the one with the 4V Vgs(th) but will partially turn on the one with the 2V threshold.

You just happen to be very lucky and bought one that has a Vgs(th) less than 3V. You might not be so lucky with the next one you buy or even the next 1000 you buy

The term “logic level” is a meaningless marketing buzzword.

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Thanks for the explanation sir, yep you're right I forgot to draw the resistor on the Led.
D3 Led is a HPL Led at 3.2V with a current around 3.5A.

Thank you all for the explanation. I'm gonna do some more experiments (maybe with Logic Level Shifter)
Have a nice weekend all.

Do not use a logic level shifter with a MOSFET transistor. Instead, buy a logic level MOSFET, after looking through the data sheets. You want very low Vgs(th) (2V is common) and the lowest possible Rds(on).

It is also very helpful to look at the performance curves in the data sheets, especially curves like the one posted above in reply #2.

Note the dramatic difference in the curves show below, for the IRLZ44 (a logic level MOSFET), compared to those reply #2, for the IRFZ44 (not logic level).

Thanks again, I think I found one IRLB3034PBF Datasheet(PDF) - International Rectifier
Easy to get here in Indonesia for .60 Dollar.

The IRLB3034PBF is a very good choice. The characteristics show below are excellent.

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That is OK for the Nano but may not work for the ESP32 depending on what is connected.

Thanks for the message, In what way it will not work for the esp32?
and is there a difference between a motor (inductive) or a Led for a mosfet ?

The ESP32 is 3.3V and there is no specification in the datasheet for an Rds(on) max at a Vgs of less than 3.3V. So the Rds(on) is unknown

is there a difference between a motor (inductive) or a Led for a mosfet ?

The motor need a flyback diode across the motor terminals otherwise high voltage spikes generated by the motor may destroy the MOSFET.

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Thanks again, Pff in my young days working with a relay was a bit easier :wink:
I'm watch now some you tube tutorials about mosfets, never to old to learn.

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