While high power LEDs need complex driver schemes, the vast majority of applications use LEDs with currents below 500 mA and can be driven by linear constant-current LED drivers. These are easy-to-use, reliable, cost efficient, and do not affect EMC. This article gives a short overview on the design and power considerations necessary to use constant-current LED drivers in practical applications.
Constant current source
For a number of applications where the load can vary, such as LED strings, the best way to ensure stable power driving is to use a constant current source. That is because these simple circuits can provide a constant steady state current independent of the load, producing an I-V characteristic represented by a straight line.