Optoisolate two ICs sharing same power supply
My focus right now is discover if it is possible to use the same supply for both ICs and yet opto-isolate this channel between them.


Notice that in the recommended circuit, the ground of the CS5463 is shown with a different symbol than the ground of the "serial data interface".

Also notice that the CS5463's ground is tied to line at the upper left.

If you connect your interface to the same ground as the CS5463 in this configuration, your entire circuit will be riding the 120 V line voltage. 

If you do not connect your interface circuit to the same ground as the CS5463, then you won't be able to use the same power supply to power the two subcircuits.

If you want to power your circuit from the same supply as the CS5463, you should use the other recommended circuit from the datasheet: