Using atom lite with 3,7V on 5V lane

  • Hello,

    I was wondering if there are any longtime consequences, when I power the atom light with 3,7V over the 5V Rail.

    I have tested it and the controller works completely normal, but I am not sure if the step-down voltage controller can handle this over a long time.

    Does anyone know the limits of the voltage controller or the exact part, that is used so I can look it up?


  • This is the answer that I got from the m5stack support:

    The circuit design of Input power is minimum 4.5V DC. So we dont suggest with 3.7V input.

    While it would not burn the board, may have some impact to the signal strength. If you are fine with the signal performance, you can use it in 3.7V

  • The problem is finding the atom lite schematic. It is not clear what voltage stabilizer was used. I suspect it has a voltage drop between input and output of ~1.0-1.2V. I connected a li-po cell (4.2V 900mAh) directly into the 5V input. I measured the cell voltage and sent the data to the local blynk server every 20 seconds. Additionally, I measured the internal temperature of the esp32 chip and it oscillated at a constant 50-51°C. With this connection the chip worked for about 6.5 hours and then turned off or stopped working properly at 3.41±0.1V cell voltage. So the esp32 chip probably stopped working at ~2.2-2.4V on a 3.3V supply line. I don't know how usb-uart converter will work with supply voltage lower than 5V. A colleague from "Esp Poland" forum tested power supply for ws2812 diode and at 3.9V the diode went crazy.
    Screenshot from blynk contain:

    • cell coltage
    • esp32 internalge temperature
    • atom lite uptime/working time