Objective Development Forums

Thanks to Grendel and Christian for your responses. I'm using a ATmega168 running at 5.0V @ 12 MHz and its working just fine. I have 68 ohm series resistors on the D+/D- lines and a 1.5K pullup on D-. I like Grendel's idea to use 3.3V zeners; I will incorporate them into my design.

Generally speaking, is it possible to use a 5V-only rated AVR (e.g. non-L suffix device, such as ATmega8/16) in a AVR-USB design? Most of the reference designs I've looked at use a 3.5V regulator to step down the 5V USB bus voltage to provide the AVR's Vcc supply. I understand why this is the case; ...