# 4-20mA output from Arduino Nano

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?

• Arduino Nano Analog Pins Output the exact voltage eg.3.3V,But the current comes 16mA(WITH 250 OHM) .It should be 13.2mA instead May 25, 2020 at 15:47
• Are you attempting to measure the PWM voltage with a DC multimeter? May 25, 2020 at 15:49
• PWM is not an analog output, it outputs 3.3V or 0V, no in between. May 25, 2020 at 16:05
• @RonBeyer Arduino Nano is 0V/~5V. There's a 3.3V regulator on board (in the USB<->serial interface chip), but it does nothing else. May 25, 2020 at 17:37
• @SpehroPefhany I was thinking of the 3.3V mini, either way, it's not an "analog output", I believe only the Due has a true analog output (DAC). May 25, 2020 at 18:35

I believe you are looking for this design

To test different levels you can change the current output by double clicking the square wave on the left and changing the duty cycle.

"analog pin" on Arduino refer to analog inputs not outputs. what you want is a DAC which outputs a voltage level. because Arduino don't have this you can use PWM and an RC filter, as shown in the above circuit

Arduino only output 5v or ground, the 3.3v output is a power supply and the level is not controllable