What happens if the voltage going into the LED goes above the maximum?
Applying too large a voltage at the diode terminals (ie, without the current limiting) will result in current above the diode’s limit, and will damage the LED. With the appropriate current limiting, though, you can use a million volt power supply to power an LED.
Does voltage matter LED?
The LED voltage VL is determined by the colour of the LED. Red LEDs have the lowest voltage, yellow and green are a little higher. Blue and white LEDs have the highest voltages. For most purposes the exact value is not critical and you can use 2V for red, yellow and green, or 4V for blue and white LEDs.
What should the forward voltage of an led be?
Another reason the test might not work is if your LED requires a high current (relative to standard LEDs) or has voltage drop greater than the DMM can supply. What you should find is that red, green, or yellow LEDs have relatively low forward voltage ranging from 1.6-2.2V.
How does the VF affect the power of a led?
It varies from color to color and by manufacturer and production lot. Vf has a big effect on the power of the LED. That is the voltage drop across the LED when current is passing. Multiply that (Vf) times the current and you get the power dissipated by the LED (watts).
Why does an LED have a constant current?
For high power, not inexpensive LEDs like the XP-G, a constant- current supply can be used to good advantage because it’ll keep the current through the LED fixed regardless of the variations in LED Vf or voltage input to the constant-current supply.
What happens when you double the voltage of an led?
If you double the voltage the current will double and the power used will go up by a factor of 4 (not quite true, there are some temperature related effects but close enough for now). An LED on the other hand is a diode, like most diodes it has a a relatively fixed forward bias voltage.