Sparkfun sells a ttl http://www.sparkfun.com/products/718 usb breakout. Allows 1.8, 3.3, and 5v sources on VCCIO. One guy posted the tx/rx LEDs did not turn off at logic level 1.8v.
The LEDs are connected to sink pins on the chip and 5v usb source. So my question is, could it be that when the pins try to close the port they can’t because the chip logic is only 1.8v and the input is currently 5v so door is being overpowered from the outside and 5v keeps flowing to ground? If so, is there a name for that? tia