An USB isolator aids remove floor loops and lowers electromagnetic interference (EMI) concerning the pc and the related device. 1x GND 3V3 (P2 with two pins 2.54mm) connector may be used to electrical power externally the WCH CH569 MCU (it is recommended to get rid of the P4/SHUNT in that case It is far from obligatory as the 3V3 LDO IC1 is secu