ESP32 Forum

Hello,

I was wondering if there is a good reason the WROOM modules specify a power supply voltage range of 3.0-3.6V instead of the 2.3-3.6 specified for the bare ESP32.

Looking at the schematic of the internals of the module (page 13 here: https://www.espressif.com/sites/default ... eet_en.pdf) it looks like there is nothing there that would require that.

I also noticed in the revision history of the wroom module datasheet that the VDD range was changed from 2.7-3.6 to 3.0-3.6 so something must be going on?

Trying to save a bit of power and want to run off a buck from a single cell down to 3V so I ideally I would like to run the ESP on 2.5V!

Thanks for all help

You could use a buck-boost to output a more reliable 3.3V from a single cell. I've had success with TI TPS63001
https://lcsc.com/product-detail/DC-DC-C ... 28060.html

The note under Figure 6: Reset Circuit says:
When battery is used as the power supply for ESP32 series of chips and modules, a supply voltage supervisor is recommended to avoid boot failure due to low voltage. Users are recommended to pull CHIP_PU low if the power supply for ESP32 is below 2.3 V

So they are recommending to definitely shut down at 2.3V. Seems risky to try to run at 2.5V or 2.7V.

The update came in the most recent revision 2019.09 V2.9 so I would suppose they discovered something that required bumping it up from 2.7V to 3.0V. I would try to follow their spec and keep it at 3.0V minimum. Otherwise you're likely to hit issues with the brown-out detector, especially if you use wifi or other large current draws that can dip the supply voltage.