I am currently trying to make a circuit to drive an LED with smallest amount of fluctuation as possible.
Background: Using an LED and spectrometer together to analyze small molecules. I can use the spectrometer to record the intensity of a light over time and that is how I read noise in an LED. I have tried a variety of LED linear drivers, and I am sticking to 5mm LEDs. My circuit consists of one driver (right now im using MAX16815) and LED, and some bypass capacitors at the IN and OUT pins.
With a DMM, I found that the current decreases/increases for 15-20 minutes before reaching a steady state.
-How can I reduce this phenomenon?
I have a 35-100mA output 3.5% accuracy LED driver with a max 100mA 5mm LED. So far, I have been working on breadboard to do testing and analysis so there could be a source of error in there. I use an external resistor to control the current output of the driver. It currently takes 15 minutes to reach any current I choose with a standard deviation of 0.007 mA. I want to reach a standard deviation of 0.001 mA just to be sure.
What can I do to reduce variations in the intensity of the LED?