High-brightness LEDs have revolutionized the lighting industry, adding more flexibility and intelligence to a variety of lighting systems, including white and colored light designs. These lighting systems allow designers to dynamically control color temperature while maintaining a high color rendering index (CRI) in white light applications. In addition, these systems produce a wide range of high precision color spectra. Although white light and color light look very different, most LED smart lighting applications are designed and manufactured using basic components such as mixed-signal controllers, constant-current drivers, and high-brightness LEDs. Multiple LED channels are typically used in white and color light designs, so all LED designs need to address issues such as device sorting, temperature effects, aging, and overall color accuracy. The use of a mixed-signal controller is a powerful and effective way to intelligently handle these problems while ensuring high-precision white or colored light. For designers who switch from traditional lighting (incandescent, fluorescent) design to LED lighting, how to use mixed signal controllers has become a huge challenge.
This article explores the similarities and differences between white light applications and color light application designs, the challenges faced by LED system design, and some powerful off-the-shelf solutions that help designers solve these problems (some without even coding).
Intelligent lighting
High-brightness LEDs (HB-LEDs) represent the future of lighting technology, and in recent years, attention has been paid to HB-LED technology. It is not surprising that people are doing this in view of the significant increase in HB-LED performance (Lumens Watts) and the sharp decline in costs (lumens). In addition, the world is actively participating in the “Green Actionâ€. Under this environment, HB-LED has even presented a strong challenge to the currently popular and cost-effective but less ecologically friendly mercury-containing fluorescent lamps. Although the high efficiency and environmental protection advantages of HB-LED are the focus of publicity, the "smart lighting" function will become an important force to promote the further development of HB-LED technology.
The application of intelligent lighting technology is quite extensive, and the only limitation is our imagination. This article will focus on one important application area in smart lighting - dimming. In the past, dimming mainly refers to adjusting the light and darkness of light, or manipulating the scattering pattern of light through optics. In the case of HB-LEDs, dimming means manipulating different characteristics of light. First, designers must consider what type of light to generate: white light, colored light, or both. For white light, the designer can adjust the color temperature and color rendering index (CRI). In the case of colored light, the designer can mix the entire spectrum of colors from the same fixed LED channel group based on the number of LED color channels used in the system. By mixing the colored lights, white light and colored light can also be generated on the same illumination device. This flexibility does lead to an increase in complexity and a trade-off between each system. Fortunately, although the white light system and the color light system look very different, in fact they are basically the same design method.
HB-LED system design
Each intelligent lighting system includes the following basic building blocks (Figure 1): HB-LED, some type of power topology (only the switch mode regulator is discussed in this article) and mixed-signal controllers. The first challenge for designers is to choose LEDs. Major LED suppliers include Lumileds, Cree, Nichia and Osram, whose products are rated for power and current, scattering patterns, color, efficiency, form factor, heat dissipation characteristics, bins, and number of LEDs per package. There are different. These parameters are the same for both white and colored light, but white light also takes into account color temperature and color rendering index CRI.
The limitations of advanced industrial design and market demand often help to narrow the selection of most LED characteristic parameters. In most cases, designers should focus on the thermal characteristics of LEDs, especially for small form factor devices or applications where space is limited and large heat sinks cannot be used. Similarly, optical technology helps to alleviate the problem of poor scattering patterns, while mixed-signal controllers can significantly reduce the limitations of temperature and device sorting.