Hi, I'm a starter here! I am trying to build a buck converter without the use of any IC. I want to drive a single LED. Here are some calculated data: Vin =5V, Vout =3.225V, Duty circle = 0.651, L=6.8micro Henri, Switching frequency = 1.4Mhz, Desired current is 1A, I also assume ripple current of 0.3+ desired Current. I am using 2 Mosfet to reduce power loss. (Source of information: http://simonthenerd.com/files/smps/SMPSBuckDesign_031809.pdf [Broken]) I have built the circuit with some components from Texas Instruments (The design is done with Pspice), everything seems to be ok. But this brings me to my first question, how can I determine the minimum PWM frequency from my calculated switching frequency? Because I will have to design a PWM generator for powering the Mosfets. I understand, since my load (LED’s resistance) is constant changing the voltage means changing the current (ohm’s law). I therefore want to control the current by adjusting the pulse width of the PWM. For this I want to use a PID controller. How can I do this? Can someone help me please? Hint: Here attached is a block diagram of what supposed to be my desirer! (Please correct me if I am wrong). I don’t want to have anything to do with digital but complete analogue! Thanks in advance.