I am using an overo air with a palo43 expansion board. I want to send data from a serial device that operates at 3.3v to the gumstix, and I have the sparkfun logic level converter(http://www.sparkfun.com/products/8745) to drop the voltage down to 1.8v. I am wondering if I can power the serial device using the 3.3v pin on the palo board? This results in a 1.8v pin being connected to the 3.3v pin through the logic level converter. I vaguely recall reading somewhere that this was inadvisable and I should use an external power source for the serial device, but I can't seem to find the source, and it would be a lot nicer if I didn't have to bring another power supply into the mix. 

Any help would be greatly appreciated,