The most reliable source for the FT231X driver is the official FTDI website. FTDI provides a unified driver package that supports the entire range of their chips, including the FT231X.
Note: Most modern Windows systems with an active internet connection will automatically download these drivers via Windows Update upon plugging in the device.
: Integrated +3.3V level converter for USB I/O. It can operate with logic levels between 1.8V and 3.3V and is 5V tolerant. Internal MTP Memory