Lately, there has been a rise in popularity in use of Light Emitting Diodes (LED) due to the advantages they provide over existing technologies. LEDs provide nearly identical output in a smaller package, consume less energy and have a much longer lifespan than other lighting technologies. In order to avoid over-powering these devices, it is important to control the temperature and current drawn by the LEDs to maximize the benefits of the technology.
To efficiently use LEDs in a reliable manner, it is necessary to limit the device current and the most cost-effective way to do this is to use a resistor. Selection of the correct resistor will involve knowledge of the recommended operating current of the LED and the application of Ohm’s Law to find the correct resistance value. Once the resistance value is identified, the power dissipated by the resistor can be determined, again by Ohm’s Law, and the correct power rating can be selected for the resistor. In most cases the resistor will only need to dissipate 1/4W or 1/2W and simple carbon film resistors may be satisfactory. For applications that require a higher power rating of between 1/2W to 10W, Riedon recommends our UT series of wirewound power resistors. For even high power ratings, greater than 10W, Riedon recommends the UAL series, aluminum housed wirewound resistors with ratings to 50W and above, with properly heat-sinking.
An additional factor to consider is the ambient operating temperature of the LED and whether that temperature would lead to device failure. One method for keeping the temperature within operating range is the incorporation of heatsinks to carry heat away from the LED. Riedon offers a variety of heatsink mountable high power resistors that would be appropriate to use in high power applications in which heat may compromise the reliability of the LED. For example, Riedon’s PFS35 is a 35W device in a TO-263 package that is designed to be mounted on a heatsink.
Riedon resistor products which are ideal for higher-power LED lighting applications. Please contact Riedon directly for a discussion of your specific application. click her to see the selection