Hi,
Thank you for the reply guys.
I think I haven't clearly explained why I would like to use the CP2102 3V3 inner voltage regular pin.
As far as I known, the microcontroller must be powered to be programmed. So some programmers and USB to UART bridges llike FTDI adapters can supply power to Atmega328p VCC pin, while with other programmers IC must be powered from the external power supply or battery.
My idea is to make the onboard programmer (trough bootloader) wich can supply power to the microcontroller's VCC pin, from the inner 3.3v voltage regulator, so I can programm the device when NO external power is supplied.
I can't use USB 5v line, because there are some components in circuit which can support maximum 3.3V.
Right now I use cheap Chinese FTDI USB to UART adapter connected to :RX, TX, DTR, VCC and GND pins of Atmega328p.
It work perfectly when the device is already powered and when there is no external power supplied.
However I don't want use FTDI because of the story with reir drivers which has damaged many devices around the world. (No matter if thise were coloned IC)
So I decided to use CP2102 , which seeems to me a good alternative to FTDI, and have the internal 3.3v OUT pin, which I thought I CAN use to power the Atmega328p when divice is connected to PC for programming.
Unfortunately I haven't yet received my CP2102 adapters and IC that I have ordered, so I can't make the real life tests as I did with FTDI adapter.
Maybe I should simply put a small Mosfet betweeen CP2102 3V3 pin and Atmega328p VCC pin, to protect the Bridge IC from the "reverse / back " voltage from the ASS1117 ?
What do yiu think ?
- - - Merged - - -
Sorry for many TYPOS, I posted reply from my phone.