WHAT IS A LED DRIVER?

[gpuguy]

Hi,

I am starting electronics after a long gap. Well can someone explain me what is LED Driver circuit and why we use it ? If it is just a circuit for giving some rated current, cant I make one such circuit using a proper resistor in series with the power supply and LED?

Thanks

 

[Harald Kapp]

A LED driver is a spezialized constant current source, possibly including temperature compensation and a few more tricks. A LED driver is mainly used for high power LEDs which are driven by a higher current than standard LEDs (e.g. 5mm LEDs) and therefore produce more waste heat. It is crucial for a long lifetime of these high power LEDs to control the operating parameters very accurately (including a suitable heat sink, but that's another story).

You can use a resistor for current limiting, too. But a resistor doesn't offer regulation. If you were to use a resistor in conjunction with a high power LED you'd
- either have to sacrifice lifetime when operating the LED near its limits
- or sacrifice light output when operating the LED with a safety margin due to poor regulation by a resistor.

For standard LED indicators (e.g. as used in toys, optical gimmicks etc.) mostly resistors only are used.

Harald

 

[gpuguy]

Thanks a lot for clearing my doubts.....