3.3V on the Atmega32u4 breakout board

[clearf]

Hi All,
First time caller, longtime listener.

I'm the recent recipient of an atmega32u4 breakout board. I'm excited to start playing around with it and doing some non-arduino uC programming. I'm was looking to interface it with some 3.3v components, and herein lies my question.

I've been poking around with the schematic trying to follow everything. It looks like the 3.3V labeled on the board is coming out of the UCAP pin on the uC. Looking at the datasheet, it looks like this is provided by a 3.3v internal regulator associated with the USB input.

Here's my question: if I connect Vcc to an external 5V source (and don't run off of USB), what will UCAP be outputting? Does anyone have any insight?

Thanks a lot,
Chris

[adafruit]

the 3.3v comes only from VUSB so it may not actually be there if you dont plug in usb

[clearf]

Great, thanks for the heads up.