I was wondering if the ti.com ISO721 Digital Isolator could be used for isolated feedback for offline switch mode power supplies as in the attached schematic?
This involves a pwm controller ic on the secondary side pulsing its duty cycle through the isolator, then on the primary side this is filtered back to a dc voltage on the primary side, where it feeds into the pwm comparator.
ISO721 Digital isolator
http://www.ti.com/lit/ds/symlink/iso721.pdf
pdf scehamtic and LTspice simulation attached