To convert 1-5V to 0-20mA:
When I use 3.3V ouput from Arduino Nano Power Pin--> Iout = 13mA (which is ok).
Similarly, with 3.3V Battery -> Iout = 13mA (which is ok).
But, when I use 3.3V ouput from Arduino Nano Analog pin(PWM)--> Iout = 16mA (I can't understand this value).
At 2.5V output from Arduino Nano Analog Pin--> Iout = 13.7mA.
Is seems their is a problem using Analog pins of Arduino nano?
At present, I am not using low pass filter. Will using low pass filter solve the problem?