ESP32C3 super mini USB dropping on external power connection

[brebisson]

Hello,

I have an issue with a project based on an esp32C3 super mini board.

My project has 3 stepper drivers and therefore an external power supply.
But it also needs a PC connection through the USB cable.

The problem is that, very often, but not all the time, when I connect the power to the board, the USB connection drops (I can hear the USB out windows sound).
Depending on the power source, I might not even be able to get any USB connection..

Can you help me fix this issue?

This is my main schematics.

pcb1.png (177.48 KiB) Viewed 4401 times

This is a zoom on the ESP32C3 + power area.
The USB connection to the PC is optional. External 9-20V power is compulsory to drive the motors.
To allow the esp32 board to run from the "external" power when there is no USB, I have placed an ali-express DC-DC board to get 5V from this to power the ESP32.
Link to the DC-DC: https://fr.aliexpress.com/item/1005006308573192.html

pcb2.png (105.4 KiB) Viewed 4401 times

Schematics of the ESP board:

esp32-c3-supermini-schematic.png (316.22 KiB) Viewed 4401 times

Cyrille