Hey,
I drive my PCB with a 5V USB that comes from the PC.
My PCB consumes 50mA, and I noticed that when I connect the PCB to the USB, then the RST pin of the MCU is getting lower and then getting HIGH, causing an external reset to the MCU right after power-up.
I know that this happens due to voltage dropout, since when I used instead of the USB, a "strong" DC power supply, there was no external reset, I assume that its because the DC poewr supply can sustain the 50mA current drawing.
I have always thought that current drawing causing a consistent voltage dropout since the wires have resistance.
Now I experience that the voltage dropout is just for a brief moment at start-up.
My question is:
Why does drawing current cause a breif voltage dropout and then the voltage gets back to its normal level?
Thank you very much.