i am in hardware design of buck converter with MOSFET as switch...i have designed L and C values...i use R load....
input voltage=24v
output voltage=18v
L=1mH
C=100uF
R=100 ohm
switching frequency=48.828KHz
i use microcontroller program to drive pulse for MOSFET.....but it is very difficult for me to capture pulses and the output is very low....
can u just plz explain me what i have made mistake in my design?
Are you using an N channel FET? If so, you need to take the gate higher than the source to turn it on (and keep it on). I would use a P channel MOSFET. What is the input to the LC filter looking like?Can you see a square wave there? It should have a duty cycle equal to the input voltage/output voltage.
See my tutorials if you want to design one properly - link below... Hope these help
You need to use a PFET (as Simonbramble said) and ALSO you need to swap the Drain and Source pins on your FET, so the gate voltage is now referenced to V+ and not to the unstable voltage on the inductor!