i m an electrical student so finding difficult to follow electronic concepts.
the following page has a practical circuit of a buck converter using SG3524
http://www.fke.utm.my/fkeweb/lab/power-e/buck.pdf
here at the 2nd pin of SG3524 they hav used a potential divider circuit to vary the duty cycle.but i want the output voltage accross the resistor to be fed to the 2nd pin so that output is automatically regulated....though they have written '2' at the output terminal also but i am a bit confused about how should i feed it to the 2nd pin and i was wondering y did they give the potential divider circuit after all).i m very new to all this plz help me...
and though i have so many other question..but this one is most imp one..SG3524 has an inbuilt reference voltage of 5V..but i want the output voltage at the resistor (accross output capacitor)to be regulated at 12 V so what should i do?should i use some other regulater or giv a seperate 12v dc voltage as reference...?
and if somebdy could tel me site wer i could get a thorough discription of working of SG3524.....

 

See the attached datasheet.