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The max current for each led is described in the datasheet, there are many kinds of led with different power ratings, mw, 1W, 3W, 7W etc.
The current can be from a few mA to many Amperes depending on the model.
Its depends on the LED power rating. All the manufactureres specify the absolute maximum current that can flow into the device. refer the data sheet.Depends on the LED colour the drop across the device will change. So you must know which type of LED you are using. If not, if you know the wattage of the LED it is possible to determine. Suppose in a circuit, if you are using LED with current limiting resister(R). Drop across LED is 2V.Assuming that the internal impedance of the LED is neglegibil. The current flowing through it is given by
I = (Vin - 2v)/R.
The Power of LED for the calculated current(I) = 2V*I watts.
This calculated value shoud not exceed the wattage of the LED (like 1W, 2W, etc.)
for example the MDEXLUMMR16, it says operating current is 300~700mA. when i have a led driver with output current that varies 200mA~500mA, this means that it will not have a flickering effect on the LED?
The current variation will vary the light intensity too in any led.
As long as you are in the proper operation limit for current there in no problem with the led but you will see it varying the light output.
There is no way to have a constant light with variable led current.
The current range for the led 300~700mA gives different light intensity and more current also creates more heat