I have an Adafruit Huzzah Feather with ESP8266 board, but I think my question will apply to most all boards (as most all have an onboard regulator). Most regulators have an Enable pin (EN) as does my Adafruit board. Apparently, I can shut down the regulator by pulling this pin low. I have a specific application where an external device will provide a high signal to me when I want the device to turn on, otherwise, I want it off at all times. So, what I have is a 1k resistor pulling the EN pin low, to ground. I tried other values 10-20k but they did not pull enough low to shut down the regulator. For example, 20k pulled me down from 3.3V to 2.6V but the regulator stayed on. On the other hand, 1k pulls me down to .3V on the EN pin and this shuts it down.
Then, when the external device gives me the high signal, which I have also tied to the EN pin, this will pull it back up and turn on the regulator.
This seems to be working just fine, but I wanted to ask if this sounds reasonable (I know this is a general question but I want to know if there is a better way). A specific, related question would be am I wasting too much power by using a 1k resistor when powered up or pulled high since some of the supply current will be dumped via the 1k resistor to ground.
UPDATE: In looking at the schematic on the Adafruit site, it appears that they have pulled EN to the input via a 10k resistor. So, I am fighting that which is probably why values over 10k do not pull it down enough to turn off. If I was doing the board design, I would have reversed this and pulled EN low by default but this is not the case when using the off the shelf board. So, I guess any value below 10k should work, like 4.7k? I guess I could also remove their pull up if I wanted to get really crazy. Thoughts on all of this?