UCC2897A: FB signal derived from coupled inductor

Hello Stanley,

I examined the MAX5974A/MAX5974B data sheet.

These devices were specifically designed to use a coupled inductor to derive the FB signal.

The MAX5974A/B show a sample-and-hold circuit at the FB pin in the block diagram.

Here is the actual schematic from the MAX5974A evaluation board.  Note that the FB pin is not "open".  It is connected to the R3/R11 node at the top of the schematic.

I then looked carefully at our UCC2897A data sheet.  It does not mention coupled inductor feedback or shown a S/H circuit at the feedback pin.  All discussion is about opto-coupler type feedback.

So, I'm fairly certain the UCC2897A cannot use coupled inductor feedback.

Regards,

Eric

Hi Stanley,

I have asked two of my colleagues about TI parts that can use coupled-inductor to the FB pin.  I hope to have an answer today.

Regards,

Eric

Hi Stanley,

There are 5 tested reference designs using the UCC2897A that meet or exceed the electrical specifications.  There is a 1/8th brick design (PMP7451.1) but the 1/16th brick requirement will require a bit of effort.  Here is a link to all 5 designs:

https://www.ti.com/reference-designs/index.html#search?vinmin=36&vinmax=60&iout=10&vout=12&isolated=Isolated&intype=DC

Regards,

Eric