I am designing a PSU capable of producing 5 watts @ 5V 1A. The design will power about 12 RGB LEDs (totaling about 400mA @ 5V) and a audio class D 1.4 W amp. Space is no issue but efficiency and cost at low quantities is!
Note: I built a flyback design where space and size were a huge issue and the transformer worked about to be a very difficult problem to surpass. I ended up going with a $16 transformer... So this time around I started with a different approach after looking at transformers that are 9$ and take 120VAC to 10VAC @ 1.3A... So here where I started:
A plain and simple design
Vout into a linear regulator and done... only the efficiency will be horrible burning between 1 to 3.3 watts in heat
Vout into a DC-DC buck converter? My thoughts are that if Vout stays well above the minimum voltage of the buck then it should function even with the large ripples.
I have read a lot that flyback is the way to go in my situation but the difference between a $16 and $9 for a transformer at a qty. of 1 is huge to me. Most of the flyback designs call for a custom transformer and this is just not feasible to me. I know I am not in the norm as I plan to build between 10 to 100 of these but, am I justified in my thinking or just ill informed on this design process?
Is it ok/safe to feed the Vout ranging from 7V to 13.5V @ 120Hz into the buck converter?
Vout while drawing a mean of 1A