This is a cheap alternative IC for the FTDI chip to provide UART over USB.
- CH340DS1 File:CH340DS1.PDF
Vendor ID: 1A86
Device ID: 7523
Manufacturer: Jiangsu Nanjing QinHeng Electronics Co
Locally hosted driver for Windows 7: File:UART CH341 W7.ZIP
I had success with these drivers on a $3 (YES!) Arduino Nano clone board from China.