Is this the same part? Is it compatible? It seems to have the same part number as the one given in the arduino's eagle file, but I just want to be sure.
arduino has no 3,3V regulator. Its 3,3V-rail is out of the FTDI-chip.
Your link is a OP-amp. It’s used in the 2009 as some sort of autopower-sensing comparator. (but don’t ask me details
Yeah the FT232RL actually has a built in 3.3V regulator that it uses to supply its some of its own internal logic that needs 3.3V and it also shares the output of this internal regulator with the outside world.
Be careful though because this pin can only supply max 50ma according to the FT232 datasheet! You don't want to fry the FT232
As Pumbaa said the Opamp is used as a comparator which basically automatically switches the supply from USB to external using the little mosfet on board. Thats one of the main differences between the Diecimila and the Duemilanove.
doh, I'm hitting myself now as my memories flood back into my brain. Yea I was taking apart the eagle files for the mega a few months ago and by now I forgot some of the components and their functions. Thanks for reminding me tho, I almost pulled a big fail there.
Now if its the FTDI giving this... What signal levels does it give out for rx / tx 5v or 3.3v ?
The FTDI chip and be wired for 3.3v or 5v logic levels depending on how it is wired up. The standard Arduino configuration is wired for 5volt logic.