Electrical – Low power ESP8266 LDO or switching regulator

esp8266ldopower supply

I'm going to use 1S Li-po, 3.7V. ESP8266 needs 3.3V and it takes 350mA peak on startup. When running it needs about 70mA.

The ESP task is to wake up, measure, connect to wifi and post data to server. It will wake up every 2 hours. I'm wondering which regulator is better for low power modules, LDO or switching. I know that LDO efficiency is a lot less efficient but they have lower quiescent current. On the other hand the switching offers better efficiency. Which one I should use?

Best Answer

Good discussion already. I'll summarize the linear option as an answer.

  • A datasheet for the ESP8266 says that it can tolerate from \$3.0\:\textrm{V}\$ to \$3.6\:\textrm{V}\$.
  • A 1S Li-Po starts out almost \$4.2\:\textrm{V}\$ with low load and is nearly empty by about \$3.4\:\textrm{V}\$.

That leaves only about \$100\:\textrm{mV}\$ of headroom towards the end of battery life and that's probably not enough. It's almost certain that you'll need at least twice that much, using an LDO at \$70\:\textrm{mA}\$ and perhaps three times it at the initial \$350\:\textrm{mA}\$ you mentioned.

But it still may be possible to consider using a linear regulator, if you choose to operate at a lower voltage. One that is at or below \$3.1\:\textrm{V}\$. Sure. That's not much wiggle room. But at least it's non-zero. Still, you may also have to consider what else surrounds the ESP8266, too. And you've asserted the need for \$3.3\:\textrm{V}\$ but you haven't disclosed whether or not perhaps \$3.0\:\textrm{V}\$ or \$3.1\:\textrm{V}\$ could be successful. (Okay. I don't know of a fixed \$3.1\:\textrm{V}\$ linear LDO with low quiescent current. So probably \$3.0\:\textrm{V}\$.)

Given all of the above, all I can suggest regarding a linear LDO option is something like the LT1763. It may meet your needs. It's quiescent current is about \$30\:\mu\textrm{A}\$, too, and requires at most \$300\:\textrm{mV}\$ of overhead for your case. So perhaps.


Given a short search (you really should do your own), I did find this from TI: TPS783xx. The spec is below your peak startup current, but well above your operating current. And the quiescent current is extremely low, I believe.