It has 2 analog inputs and can supply 5V ont the 4 pins header on the right. One of the inputs can be scaled down with the trim pot. The firmware in the Tiny45 is written in C and compiled with Winavr and usb source code from obdev. As you can see, there is no crystal , the software sync the internal 16.5Mhz pll clock with the USB clock. Of course, do not expect 1Gs/s HID does not alow that data rate ! But it is using a 10bits AD. It has been designed to plug into a project breadboard so there is no need for a power supply.
