The USB has become a popular solution to connect PC peripherals. The USB allows devices to be hot-plugged in and out of the existing PC system without rebooting or turning off the PC. Because frequent human interaction with the USB system occurs as a result of its attractive hot-plugging ability, there is the possibility for large ESD strikes and damage to crucial system elements. The ESD protection included on the existing hardware is typically in the 2-kV to 4-kV range for the human body model (HBD) and 200-V to 300-V for the machine model (MM). The ESD voltage levels found in a normal USB operating environment can exceed these levels. The SN75240, SN65240, and SN65220 devices will increase the robustness of the existing USB hardware to ESD strikes common to the environment in which USB is likely to be used.