I have to use an Arduino Nano 3 for a project and wish to use the 3v3 output of the FTDI chip for reference to the ADC. However, it is said in the Nano 3 datasheet that the 3v3 output of the FTDI chip is not avialable when the board is powered via external power.
“The FTDI FT232RL chip on the Nano is only powered if the board is being powered over USB.
As a result, when running on external (non-USB) power, the 3.3V output (which is supplied by
the FTDI chip) is not available and the RX and TX LEDs will flicker if digital pins 0 or 1 are
But when I look into the schematic (http://arduino.cc/en/uploads/Main/ArduinoNano30Schematic.pdf) of the board it can be seen that the FTDI is powered via the 5V supply only. I want to know why is the 3v3 output not available while on external power, because as per the schematic, it should be available, shouldn’t it?