ATtiny84 usb interface help.

I am trying to build a small development board with the ATtiny84, but I am having trouble figuring out how to wire USB into it. The only material I can find on it suggest that I need to buck the input down to around 3.6v but this doesn't make sense because the ATtiny84 is rated for 1.8v-5.5v. Any input on this would be appreciated and a schematic would be even better.

thanks Paul