The USB 2.0 standard says that the MAX. SPEED is up to 480Mb/s, but that doesnt mean that it has to work at that speed. There are 3 basic speeds:
- low speed (I think it is about 1,5Mb/s)
- full speed (12Mb/s)
- high speed (the usb controler tells to the usb host what speed he would like to use and that it is up to 480Mb/s)
The USB 2.0 is compatible to USB 1.1 that means that you can connect a USB 2.0 device to a USB 1.1 host, but you are limited to low and full speed.
There are a lot of USB 2.0 devices (and controlers) that can only connect with low and full speed on USB 2.0 host, but not with high speed.