rHow to connect MOSFET as power switch in Buck Converter?

Thread Starter

exynos

Joined May 21, 2023
5
hello everyone, I'm now making a Buck converter with tlc555 ocillator.
But there's a problem with using nmos as switch.

1689233061500.png
The left part is ocillator and the right parts is buck converter with capacitors in parallel(to increase capacitance).
I have to use nmos as switch but that connecting method doesn't work.

I refer to The Art of Electronic 3/e.
I used that method for connecting but doesn't work.
1689232657293.png

How do I connect N channel mosfet to function correctly?

1689232685828.png
I have 2N7000 and IRFZ44N.
I use regulated DC power supply as input.
 
Last edited:

ericgibbs

Joined Jan 29, 2010
19,078
Hi ex,
If your power lines for the bread board are as I believe, then the 2N7000 Source pin is at +Vs.

Also, when driving a tungsten lamp, the initial current will be approx 5 times the normal operating current, so you may be damaging the 2N7000.
E
1689232365796.png
 

Ian0

Joined Aug 7, 2020
10,228
"In order to help another effectively, you must understand what he understands.
Instruction begins when you put yourself in his place so that you may understand what he understands and in the way he understands it". Soren Kierkegaard
That’s very good. I see so many threads where we spend two or three pages trying to reach that point.
 

BobTPH

Joined Jun 5, 2013
9,251
Just FYI. The high side gate driver is designed to overcome the problem of using an N channel MOSFET as a high side switch.
 
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