ESP32 is becoming a popular and potential game-changer in the IoT
industry. Once a code completed, to take off without a USB power,
questions rise about powering it; What’s the feasible external voltage
range? What’s the current? Which cell battery? And so on. These
questions cannot be quickly resolved by only skimming datasheets.
This paper went over to clarify the obscure information about the DC
supply range for the ESP32 development board, especially ESP32-DevKitC
V4. The investigation, calculation, experiments, and LTspice simulation
disclosed the result. Starting from getting relevance facts from
datasheets of essential components on the board, calculated thermal
conditions of the heated element, experimented to confirm the deliberate
and get empirical data while code running including GPIO and WiFi, and
ended with simulation ensure the data.
This paper concludes the following result points. The minimum supply
voltage is 3.6 V to run an ESP32 module. The supply voltage should be
under 10 V for both input capacitor rated voltage and LDO junction
temperature rating. The thermal restriction was calculated at an ambient
temperature of 25 °C and tried and tested. For a more harsh environment,
this way could derate the upper limit voltage. An external power should
supply current well over average 100 mA, a good 1 A. In terms of
battery, this range reassures that an ESP32 can run with a single cell
LiPo. Regarding the USB, both the high power and low power port can
supply sufficiently. While an external supply being no less than 5.2 V,
both the USB and external sources could work simultaneously.