LEDs have also been used as a medium-quality voltage reference in electronic circuits. The forward voltage drop (e.g. about 1.7 V for a normal red LED) can be used instead of a Zener diode in low-voltage regulators. Red LEDs have the flattest I/V curve above the knee. Nitride-based LEDs have a fairly steep I/V curve and are useless for this purpose. Although LED forward voltage is far more current-dependent than a Zener diode, Zener diodes with breakdown voltages below 3 V are not widely available. COUNT 5
QSN1 What quality has LEDs been used as? ANS1 medium-quality QSN2 What LED has the flattest I/V curve above the knee? ANS2 Red QSN3 What LEDs have a very steep I/V curve? ANS3 Nitride-based LEDs QSN4 LED forward voltage is more current-dependent than what diode? ANS4 Zener QSN5 Zener diodes below what voltage are not widely available? ANS5 3 V