It is well known that the luminescent properties of LEDs are highly dependent on their operating conditions. The forward current applied to the LED is the main influencing factor, and the higher the current, the more luminous flux the LED produces. Unfortunately, the LED is driven by a constant current source, and as the temperature of the LED rises, its light output drops dramatically. Figure 1 shows the effect of common LED basic parameters on the output spectrum. In addition, this figure also shows that the efficiency of the LED and the color of the luminescence also shift at the peak wavelength.
Figure 1: Effect of current and temperature on the red LED output spectrum (click on image to enlarge)
The importance of LED thermal characteristics
Since the light output of an LED changes with temperature, good thermal management is an important issue in power LED lighting applications. By lowering the temperature of the LED, we can maintain it at a higher efficiency. In practical applications, the lower the LED temperature, the more lumens it outputs.
This means that in the actual application of LED, its true thermal resistance from junction to environment is an important factor in LED lighting design . It is regrettable that the thermal resistance and other temperature-related characteristic parameters offered by different LED suppliers are varied. Therefore, different thermal standards agencies have also begun to work on the development of standards for LED thermal management. Today, the JEDEC JC15 Association is drafting a new standard for LED thermal resistance measurements. In addition, the International Lighting Committee has established two new technology associations (TC-2-63 and TC-2-64) to address LED thermal issues. There is a growing consensus among these associations that suppliers must consider the actual optical power Popt (in other words, the radiant flux) when calculating the LED thermal resistance using Equation 1:
The product of the LED forward current and the forward voltage (IFxVF) in the equation is the electrical power required for LED operation, and ΔTj is the junction temperature variation of the LED.
Fork Type Terminals,Insulated Bullet Sockets Terminals,Insulated Bullet Terminals,Type Fork Insulate Terminal
Taixing Longyi Terminals Co.,Ltd. , https://www.txlyterminals.com