Designers need to account for temperature factors in the early stages of the design process to mitigate heat’s potential adverse effects. Thankfully, the effects of heat in an LED system can be understood through calculation and simulation. A model that is used frequently is the thermal circuit model. These thermal circuit models are similar to resistor circuits using Ohm’s law. An LED’s power dissipation is modeled as a current source, thermal resistances are modeled as resistors, and the ambient temperature is modeled as a voltage source. The thermal resistance must be minimized to increase an LED’s light output or its useful ambient temperature range for a given power dissipation.
Minimizing the thermal resistance can be done in a number of ways. Conduction, convection, and radiation are the three means of heat transfer. Conduction and convection are typically used to transfer heat from LEDs to ambient temperature. Convection requires the movement of air, which in many instances requires a mechanical means of moving air, such as a fan. In many cases, fans are not an acceptable way of cooling LEDs in light fixtures due to noise and reliability concerns. Conduction, however, is the transfer of heat from one solid to another, and is typically the way LED systems are cooled. Conduction requires the accurate design of heat sinks to properly cool an LED system in its intended environment. This is where the thermal circuit model is valuable. The thermal resistance value of a heat sink can be calculated for the specific LED system and its temperature environment. This information allows for the proper selection criteria for a standard heat sink or provides the information needed to design an effective thermal management system.
Designers at Norlux are experienced in LED thermal management and the design of thermal systems. If you are facing challenges regarding LED performance and LED heat dissipation, contact Norlux for a solution that’s ahead of the curve.
