The 3.3v FTDI cable:
http://www.sparkfun.com/commerce/produc … ts_id=9717
We have discovered that the internal connections are a bit different than what they should be.
The schematic on the web page indicates that Vcc on the female header of the cable is connected to the 3.3v regulator output from the FTDI chip. Vcc on the female header is actually connect to the 5v Vbus supply from the USB connector. So don’t plug the header into some super sensitive IC.
There should be an update on the product page soon.