Low Power Design - What comes first?

[englishdogg]

Let's say we ahve a domain A and domain B. both these domains operate at different voltages and are switchable as well.
Since they operate at different voltages - that means we need a level shifter; also since they are switchable we also need an isolation cell

My question is which would come first a ISO + LS or LS + ISO?

 

[dean_winchester]

ISO + LS is the feasible option i guess..
since only one of then will be operatable at any moment.

 

[dftrtl]

ISO --> LS is Best option

 

[englishdogg]

Agreed.. but what could be the problem when we have LS + ISO