I am creating simple expansion board for my Raspberry Pi with a few I2C components (EEPROM, RTC,...) and I would like to add a USB to serial converter to be able to connect to the RPi's serial port for debugging purposes (console access).
Until now I've been using a simple module with CH340 and I've decided to "just move" the chip onto my expansion board. Unfortunately the official CH340 datasheet is only in Chinese and the unofficial translation is not detailed enough.
I am not sure how to power the chip. In all examples it is powered from the USB port via voltage regulator (I need 3V3 logic for my RPi) however I have 3V3 available from RPi and I would like to power the CH340 chip from it to avoid using additional voltage regulator. Is this possible or does the CH340 need to be powered from the USB port?