In my application I need a +12V output on the high voltage rail and a floating output. I'd like to use the high voltage rail output to close the loop and trust the magnetic coupling to provide reasonable regulation of the floating output. It seems this part must be married to a 431 regulator for loop control. Is there a simpler way of providing local, non-isolated feedback to the FB pin and obtain reasonable accuracy and regulation?
Hi
We have dedicated primary side regulated (PSR) converters that satisfy your requirements.
I recommend considering UCC28704 first, it is our latest PSR flyback controller that has all the same advanced control features that enable high performance.
UCC28704 has a fixed cable compensation (CBC) though, where the output voltage increases with output current to compensate for conduction losses for charging cable. Figure 17 from the UCC28704 datasheet provides more information about this (shown below). While this is a benefit for applications where there is a sizable impedance between the AC/DC supply and the load (such as a USB charger with a long cable), not every application requires such a feature. If it's not needed it can cause an undesired reduction in the output voltage regulation accuracy. If this cable compensation feature is something that's highly undesired, we recommend you consider our previous generation UCC28700 PSR flyback controller, which can adjust or disable CBC.
Best Regards,
Eric
