From the Block diagram what I understood is there is 1.8v/3.3v regulator output from PMIC and this can be controlled via sending some commands.
I'm confused ,then how is this possible "When you disable 1.8V, the memory chip will stop working, the processor too.", we're just turning OFF 1.8/3.3V ouput of PMIC right?
Your diagram is incomplete. You assume that there are multiple voltage regulators: like two 1.8V regulators, the first one for the module itself, the second one for external devices. But it's not true.
Intel® Edison uses the Texas Instruments* SNB9024 Power Management Integrated Circuit (PMIC).
- One single-phase 1.8 V @ 1.1 A
You turn it off, you turn off the Edison.