I'm working on my personal project for school. In this, I want to run 12 V 1 A motor using a IRFZ44N MOSFET using an ESP32 but as we know, the IRFZ44N needs 4 V to completely turn on and ESP32 pins provide only 3.3 V at 20 mA, sonot enough to turn on MOSFET.
I searched the internet for the proper transistor and I found a common transistor (BC548) which is in my box now. I have drawn a circuit to drive the IRFZ44N. Will it work?
Here is a simulation of the circuit, showing a 3.3V GPIO signal driving a 1 amp motor (simulated by a 100 mH inductor with 12 ohms series resistance)
simulate this circuit – Schematic created using CircuitLab
The transistor needs to be connected with its emitter tied to ground, called "common emitter".
As you have it, in a configuration called "emitter follower" or "common collector", the emitter of the transistor is always 0.7V below the base, and since the base never rises above +3.3V, the emitter can only reach +2.6V. That's not even close to what you require at M1's gate.
In the following circuit, M1's gate is +5V when the ESP32 output is low (0v), and 0V when that output is +3.3V:
simulate this circuit – Schematic created using CircuitLab
To switch the motor on, you require a low output from the ESP32.
R2 prevents the motor from running before the ESP32 has configured its ports, by gently holding that output high.
I just noticed that you can further improve this by connecting the top of R3 to the +12V supply, instead of +5V. That way, M1's gate can rise to 12V, easily enough to get the best (lowest) possible drain-source resistance \$R_{DS(ON)}\$.
Seems like your MOSFET will never turn on. If your GPIO high is 3.3V, the BC548 emitter will be about 2.6V to 2.7V because of the base-emitter PN junction voltage drop. To solve this, you should use the BC548 as common-emitter configuration to drive the MOSFET.
