I want to make a 3.3V I/O (UART) interface between a FT232RL and AVR which operate at 3.3V For this configuration responsible it's VCCIO and must be connected to 3.3V supply. But what about VCC? Can it connected at 3.3V supply line with VCCIO together? As the datasheet say for VCCIO
+1.8V to +5.25V supply for the UART Interface and CBUS group pins (2, 3, 6,7,8,9,10 11, 21, 22, 30,31,32). In USB bus powered designs connect this pin to 3V3OUT to drive out at +3.3V levels, or connect to VCC to drive out at +5V CMOS level. This pin can also be supplied with an external +1.8V to +2.8V supply in order to drive out at lower levels. It should be noted that in this case this supply should originate from the same source as the supply to VCC. This means that in bus powered designs a regulator which is supplied by the +5V on the USB bus should be used.
This which i mean that it is necessary to connect 3V3OUT to VCCIO for get 3.3V level interface? I mean: I don't want to use 3V3OUT for VCCIO supply, i want to supply VCCIO pin externaly with 3.3V line. And since i work the FTDI with internal oscillator VCC limited at 4V MINIMUM. So, VCC must be connected at > 4V supply for normal operation. Am i true?