Most arduino led blink tutorial recommend connecting a 5mm led to the 5v pin. Though, most 5mm led datasheets note the maximum forward voltage as 4v. Am I missing something here? The 220ohm resistor limits the current to an acceptable limit but what about the votlage? Link related.
Max Vf is the highest voltage drop you will measure across the LED when it is turned on.
Reverse voltage is different - how much voltage can be applied "backwards" before the diode breaks down and conducts in the opposite direction.
jonhatespizza:
Most arduino led blink tutorial recommend connecting a 5mm led to the 5v pin. Though, most 5mm led datasheets note the maximum forward voltage as 4v. Am I missing something here? The 220ohm resistor limits the current to an acceptable limit but what about the votlage? Link related.
Remember that thing called Ohm's Law?
How many volts do you need to push 20mA through a 220ohm resistor?
The 220ohm resistor limits the current to an acceptable limit but what about the votlage?
If the current is limited so is the voltage dropped across the diode. There is not a maximum forward voltage drop for an LED only a maximum current. Get that right and the voltage is within limits.
As Crossroads said that specification is for reverse voltage that is when you wire it up backwards or apply AC to it.