Green LED I-V Curve

Ricketty C · 2020-07-15T04:36:22+00:00

I was thinking of using a green LED to limit a measured voltage on the ADC of an MCU. However, I can't find a good chart of the I-V curve below 1 mA. The circuit supplies up to 1.15 mA which is measured by dropping it acros s a 1.5 k resistor yielding up to around 1.7 volts. This seems like it mig ht be getting into a range where the LED might be stealing a significant po rtion of the current being measured. But none of the references I can find provide enough detail to know for sure. Most seem to be something along t he lines of an "artist's concept" of a curve lying along the X axis until r eaching some voltage where it takes off like a hockey stick. Others just s eem to be a wag with only a very few points measured. None of them show an y detail at the low end with 10 mA as the lowest line on the Y axis. Anyone measured a green LED at low currents or know how they respond? If needed, I can lower the resistor which will lower the voltage the LED wi ll see, but I can't lower it too much or lose resolution of the measurement . Maybe I should just give in and limit the voltage with a Zener diode. I wa s trying to keep a part off the BOM if possible. There's already a green L ED in use. -- Rick C. - Get 1,000 miles of free Supercharging - Tesla referral code -