AC164114 is a PIC18F1xK50 Programming Adapter designed to prevent damage to the USB PIC Microcontroller during programming. It limits voltage at the VPP pin to 8.5V, and also prevents the voltage applied to D+/D- from exceeding 3.6V when Vdd to PIC18F1xK50 is greater than 3.6V. In addition, it automatically protects USB data connections during the program/erase cycle thus, the USB cable does not need to be unplugged from the USB host during these operations.