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.