An USB isolator allows eliminate ground loops and lowers electromagnetic interference (EMI) between the computer as well as connected product. 1x GND 3V3 (P2 with 2 pins 2.54mm) connector can be employed to energy externally the WCH CH569 MCU (it is suggested to eliminate the P4/SHUNT in that case It's https://confuciusm062nkd6.wikipublicity.com/user