NLED Project Guide - Loose & High Wattage
Loose High-Wattage LEDs:
Standard LEDs: Covers SMD packages and epoxy cast packages like 3mm, 5mm, 10mm. These types of LEDs come in a variety of light colors, packaging, and lenses. SMD types usually have a clear lens that adjusts the viewing angle of the LED. Epoxy cast packages come in different sizes, in either clear, diffused white, or colored lenses. Colored lenses do not affect the color of the LED, clear lenses change the LEDs viewing angle. These types of LEDs commonly use 20mA to 100mA.
High Wattage LEDs: These types of LEDs are large and bright, and normally mounted on heatsinks(commonly called stars), that are then thermally attached to even larger heatsinks. They require high currents and produce a lot of extra heat that must be dissipated through a heatsink to prevent damage and degraded life expectancy. These types of LEDs should only be controlled with a constant current controller or regulators, using resistors produces too much power waste to be effective.
Current Regulation:
LEDs can not limit the current that flows through them, given the opportunity they will draw so much current they will burn up the diode. No LED should be powered up with out current regulation, LED pixels have internal current regulation and are powered directly from the power supply.
Constant Current: The best way to limit current, it is the most power efficient and safest way to power LEDs. Constant-current regulators come in many sizes and capabilities, they come as small as SOT-23 SMD sized for current regulation as low as 10mA, or larger multi-component circuits that can produce high currents. The constant-current regulator must have the same output current(or less) as the LEDs require, some are output a fixed current, some methods have adjustable output currents. Smart/Addressable pixels have internal constant current regulation and do not require any additional current regulation.
Resistors: Suitable for low current standard LEDs, quick and cheap, just add a resistor in series with it. See online calculators for help choosing resistor values for various LED forward voltages.