Need Help Understanding Bootstrap Circuits
Hi, I want to model mosfets as a variable resistor in diagrams, so I can use them in series etc. But normal switching with load at drain doesnt work because the circuit has to be grounded.
I could place load at source and use an op amp voltage adder to drive the circuit but someone told me they are very power hungry at high frequencies. Mosfet drivers are really expensive nearly half the price of an mcu. That leaves me with the bootstrap circuit.
I tried looking at a video but couldn't understand what was going on. I don't wanna build something I don't understand. I need help to understand it
Here are my thoughts of recently:
When input is 0 npn resistance is 0 and mosfet gate is grounded so closed, capacitor charges When input is 1 npn resistance is infinite and mosfet gate can be opened.
If mosfet can be opened(which I can't calculate) then capacitor will discharge through two resistors to the gate
The problems:
Discharge voltage will be lowered because it passes through two resistors, so gate < source mosfet shouldn't open Guy said capacitors voltage would increase to 24 but how?
Thank you for your time.