Hi, I have connected my controller (ATMEGA2560) input to 5V power supply. At the VCC terminal 5V is shown. The VCC, TX,RX, RESET and GND pins are connected to a FTDI programmer port as shown in figure.
The diode D(SS34A) is connected in series of the VCC line from controller to FTDI programmer port, so that it forms a reverse bias from controller to the FTDI programmer. The 0.1uF capacitor is connected only to supply a stable voltage to the controller.
But, when I connect my FTDI programmer to the FTDI programmer port with other end of the programmer not connected to the USB terminal, I found 5V at the VCC terminal of the FTDI programmer, which should not happen.
So, How the 5V is coming in the VCC terminal of the FTDI port at this condition ?