I'm looking at designing a LED driving power supply that can interface with a universal AC main input (~90VAC-260VAC) and produce 2 rails at the output; one a current controlled rail, and the other a fixed voltage.
In the interest of reducing cost, and since I'm looking at about a power rating of around 40W, I decided a flyback topology would be most suitable for my needs.
Is there a method for Flyback converters - or any other SMPS topologies for that matter - to provide BOTH a current controlled rail and a fixed voltage rail without significant increases in parts count or cost? As far as I can work out, the relationship between the secondary side rails prevents this.
At this point i've not found a solution and I think that i may have to implement either a second converter for the fixed voltage rail, or piggy back on the converter IC's primary side voltage source.
What options do I have for this kind of setup?
Thanks in advance.