5Pcs CJMCU-340 CH340G TTL To USB STC Downloader Serial Communication Module Pin All Leads
There seems to be no documentation on how to convert the voltage level to 3.3V, this is how I done that - 1. Remove 0Ohm register link above the voltage regulator to decouple the IC VCC to USB VIN 2. Bridge three exposed pads using solder to connect the output of the voltage regulator (3.3V) to IC VCC and IC internal reference