Is the FW supply listed on a LEDs tech specs the same thing as the voltage drop?
I have never seen a FW supply listed in any data sheet for an LED, such a thing does not make any sense.
On the back of the packaging of an LED from Radioshack
FW supply: 3.3V (typical), 4.0V (max.)
Does this mean you should plan for and use resistors for this max setting (in this case, 4.0V)?
Or is the best method for figuring out an LEDs voltage drop what Duane explained above?
as they age this value will change
Any real life experiece with that?
Data sheets don't tell anything in this direction
QuoteData sheets don't tell anything in this directionYes the do they give a maximum and minimum range for this parameter.
QuoteAny real life experiece with that? Yes
It it usual that VF will grow with age
I understand (now, thanks) that the "typ." and "max." values for VF are not only individually different, but may change over time for a given led.
It it usual that VF will grow with age ( making current decrease in a given resistor controlled circuit )?