ESP8266 Community Forum

I am working on a new design using CH340g as the USB to rs232 converter. I am finding conflicting information online researching the CH340G VCC input. Unfortunately I have a dev board with a different rs232 ic so I cannot just probe it.

The datasheet is showing that the VCC input can be either 5v or 3v3. I assume that changes the levels of rs232 i/o. I would therefore think to use 3v3. But this Node MCU schematic for CH340G has a 5V input. I assume 5V i/o could damage the ESP8266

https://raw.githubusercontent.com/nodem ... IT_SCH.png

Effectively, 5V on CH340 produce 5V on i/O. So, this NodeMCU is not well design, but at least they placed R10/R12 resistor to prevent damages, limiting the current on the internal protection diodes of the ESP.
In you own design, you should power CH340 with 3.3V, like most USB-TTL dongle are doing.

Thanks, that is what I figured.