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.

  • \$\begingroup\$ Your questions are much too broad in scope for a practical answer. Google "LED power supply" and "SMPS" and "Flyback converter" to get more answers than you can read in ten years. \$\endgroup\$ – Sparky256 Jan 29 '19 at 5:54
  • \$\begingroup\$ All SMPS I am aware of generate output voltages in the ratio of their secondary turns at least initially so need some sort of post regulation. If the topology is forward i.e. 'buck' derived a magamp on one of the outputs is an option. For a 'flyback' a separate 'buck' or linear output stage may be appropriate depending on power level required. \$\endgroup\$ – Warren Hill Jan 29 '19 at 12:13

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