i have made a smps +12v-0--12v. using i.c. 5l0380r. i have taken the feedback from positive supply only
but the problem is the negative output not steady. how can i make both supplies stable?
I had same problem with different chip from (Power integrations), and I had no success to make it working at all. even PI themselves gave no solution to that problem, eve you may find my discussion with them at the PI forums.
After digging into the web, I found a Russian solution for that problem, witch is to use the feedback as it is, and to increase the output voltage for example up to +-30VDC, then insert your voltage regulators there, and you are done.
I had no time to test that circuit, however, same issue and same problem was clearly indicated in Fairchild Chips, the confirm there is a voltage variations , because of feedback.
I don't know how these companies just manufacture these chips without testing such circuit.
Good luck