Greetings all,
This is my first time playing with active power factor correction (APFC) IC.

With parametric searching at Element14, I found that FAN7527BN is the cheapest among all.

Doing my homework on the net, I decided to try to build one for myself. Here are the references.

http://www.fairchildsemi.com/an/AN/AN-42047.pdf
http://www.fairchildsemi.com/an/AN/AN-4107.pdf
http://www.fairchildsemi.com/an/AN/AN-4121.pdf
http://www.fairchildsemi.com/an/AN/AN-6027.pdf

My curiosity is inhibited by the use of smps transformer with specific characteristic required by the IC; which is hard to get by me.

I really prefer to use just an inductor as the energy storage device, and separated power transformer for the IC supply.

I don't mind if changing the IC is required, as long as the circuit is simple enough for me to comprehend, possibly, doesn't cost too much.

Any advice? Thanks.

 

I don't know, info in links looks detailed and very clear.
for example you get inductance, wire size and number of turns, part number for T1 which you can lookup on manufacturer's website etc.

the "transformer" in circuit is really just a coil. the 'secondary' is there merely for zero cross detection, not for energy transfer (did you actually read the linked files?)

if primary is 44 turn and secondary is 6 turn - you have the turn ratio (and making 6 turns of thin magnet wire is not exactly hard labor).

you could also just get inductor of proper inductance (400uH) which can operate at required frequency (36kHz) and current, then count existing turns, and add own secondary using same ratio. a toroid would be easy to modify.

 

As I said in the previous post, the IC needs transformer with specific characteristic.
I do not own any LCR meter as it is too expensive for me.

I might just end up ordering simple inductor on Element14 as the value is already specified.
I could just wind my own toroidal transformer, I do know it's trivial, but I'm blind, no way of measuring the inductance.

Core characteristic is another different thing, I have a box of random toroidal core, but how could I choose it without prior knowledge?
My experience is limited, hence I'm posting here.
The only tool I have relating to inductor is the inductor saturation tester, which is homemade, replicated from Alan Yates website.

Another question is, what determines the turn-ratio? It is quite hard for me to digest all of the information on the appnotes without proper guidance.

I'm planning to make toroidal transformer with litz wire, this is my first time,
hoping you guys could suggest some advice, backed with knowledge and experience.