Kategorie: Laboratory

This blog post explains the easiest way of powering up the ESP32-CAM board: Connecting an external power supply to the input voltage pin 5V on the board.

On the ESP32-CAM board, the soldered voltage regulator AMS1117-3.3 (read more about the AMS1117-3.3 here) regulates the voltage connected on the input voltage pin 5V. It delivers an output voltage of 3.3 volts and a maximum current of 1.5 amperes. To this end, the voltage regulator requires an input voltage greater than 4.5 volts due to a dropout voltage of 1 volt. In detail, both a laboratory power supply or a battery-based power supply can deliver the required input voltage.

Laboratory Power Supply

The function of a laboratory power supply is to supply a constant voltage (typically indicated by „C.V.“) or a constant current (typically indicated by „C.C.“). It converts an unregulated alternating current (AC) into a constant direct current (DC). Usually, a laboratory power supply delivers a variety of continuous or preset voltages (read more about regulated power supply on Wikipedia).

Now, it is time to power up the ESP32-CAM board with a laboratory power supply that delivers the constant voltage required:

1. Set the output voltage of the laboratory power supply to a fixed voltage between 5 volts and 6 volts
2. Connect the output voltage of the power supply to a ground pin GND and the input voltage pin 5V
3. Turn on the voltage supply of the laboratory power supply to provide the required input voltage of greater than 4.5 volts to the AMS1117-3.3

That’s it. The external power supply together with the AMS1117-3.3 power up the ESP32-CAM board.

Battery-based Power Supply

A battery-based power supply delivers an output voltage, depending on the type of the battery. For instance, a Lithium-Ion Polymer (LiPo) battery delivers an output voltage of 4.2 volt, if it is fully-charged. While discharging, the supplied output voltage decreases to 3.7 volts. Please note that the output voltage of a LiPo battery should not reach 2.5 volts or less – better 3 volts or less. Otherwise, it could permanently damage the LiPo battery:

Due to the required input voltage of greater than 4.5 volts, the number of needed LiPo batteries is two LiPo batteries connected in series:

In detail, two fully-charged LiPo batteries connected in series supply an output voltage of 8.4 volts to the AMS1117-3.3, powering up the ESP32-CAM board. While discharging, the two LiPo batteries supply an output voltage of 7.4 volts, decreasing to an output voltage of 5 volts. To prevent the two LiPo batteries from a permanently damage, completely disconnect the two LiPo batteries from the electrical circuit, latest reaching the critical low voltage of 5 volts – better 6 volts.