I want to sense brightness via an OSRAM SFH3310 phototransistor by using an ADC (Vref 3.3V - teensy 3.1).
I understand that I need a voltage divider to get a good ADC reading. In the past I simply connected a potentiometer and tried out which resistance value maxed out the ADC value. The best value I figured was 120k.
I would love to understand the datasheet more precisely, to have a more engineered approach :-)
From this diagram, I would derrive, that at 3.3V at 20lux (almost dark), I would have a current flow of around 5uA. According to Ohms law, this would mean a resistance is R=3.3V/0,000005A= 660kOhm? In brightness I read 70uA, R=3.3/0,000070A=4.7kOhm. Do I use these values for R1 in the voltage divider.
I'm not sure if I got the right thinking here.
Thanks a lot for your help.