Other Parts Discussed in Thread: UCC28056,
Hello,
I have a cost sensitive application I need to have a PFC frontend for in the 250W range. A DC output of something around 400VDC +/-10% is good enough. There is a post regulated stage with isolation.
My current issue is looking at the coupled inductor on the reference design. This thing is super expensive. No way I can use that. Looking at the datasheet though, I think I can get rid of it right? The coupled inductor does two things from my 1000-ft view. First it makes a VCC voltage that is low and somewhat more efficient instead of taking it off the high voltage rectified AC. Then the second thing it does is make the ZCD pin low enough voltage.
For the VCC, I already have a high voltage linear regulator that is making a nice 12VDC from the rectified AC. I also have an auxilliary winding on the next stage that makes a nicer 40V that could make VCC more efficient if I need. So assuming I don't care about efficiency and just use the linear regulator, I don't need the coupled inductor for that.
For the ZCD, can I not just use a resistor divider off the D1/Q1/L1 node to get the same effect?
Since I am making a custom board for this as it is obviously a non-standard use case, I'd like to make sure this is possible. Especially since I can't simulate it in LTSPICE :(
Thanks