ESP8266 Community Forum

Does disabling the chip via the EN pin save power? How much miliamps does the whole thing draw when chip disabled?

Pulling CE down is almost equal to removing the power, so yes, it really does save power, only a few microAmps, maybe nanoAmps left. The downside is that when you bring it back up, the ESP8266 needs to start just like it would have to do after power is applied.

So personally I don't think it's that useful, it's almost equal to taking away power and then re-applying it.

The only difference is that RTC keeps running and can be used to wake the chip after a set time.

EN can be very useful in battery powered applications where you have an external signal that can be used to control EN to activate the chip.

For example a magnetic reed switch sensor (door opening) or a PIR can be used to activate EN. The chip starts up and does whatever activation / notification is required.

In this scenario it is best combined with a diode feedback from a GPIO to keep EN high until the action is complete and to also use deep sleep to ensure the device returns to a quiescent low current state.

This method allows battery drain to be just a few microamps in its idle state.

But it won't keep state, as I think is often understood from it. The chip needs to completely boot after enable.