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DALI-2 Intelligent Tunable White LED Driver: LCM-40TW
Date：2022/10/27
What is color temperature? Simply described, color temperature is a measuring unit that expresses the color contained in light. Its concept is based on the various colors of light produced when an absolute black object is heated to different temperatures. For example, in the most frequent sunlight, the temperature is lower in the morning and evening hours, and the color temperature is warmer yellow; in the noon time, the temperature is higher, and the color temperature is cooler and whiter. The color temperature connection from 1000K to 10000K is shown in Figure 1. The lower the color temperature value, the redder the color; the higher the color temperature value, the bluer the color.
Figure 1 Color Temperature
Lamps with a single-color temperature cannot suit people's life and work requirements at the same time because people's light temperature needs vary with time. As illustrated in Figure 2 for hotel room lighting, cool white light or neutral white light is preferable for reading and communication during the day, while warm light can relieve physical and mental weariness, improving sleep quality at night. Undoubtedly, LED fixtures with tunable color temperature will become increasingly popular in residential, hotel, office, and other commercial lighting settings to provide customized lighting to fulfill the needs of different time periods.
Figure 2. Hotel Room Lighting
As illustrated in Figure 3 below, the LED lights with tunable color temperature and brightness use two sources of light output: cold （6500K）and warm （6500K）color temperature, each of which is relatively independent. As shown in Figure 4, the color temperature can be adjusted by modifying the ratio of the driving current of each light source. Under specified color temperature conditions, the brightness can be adjusted by setting the driving current of the two light sources in the same proportion.
Figure 3 Driving method of tunable color temperature LED fixture
Figure 4 Color temperature and Current value curve
With the advancement of the intelligent lighting industry, LED drivers with tunable color temperature and brightness and digital lighting control, ensure that the color temperature and brightness settings do not interfere with each other. This design has gradually substituted the "constant voltage source + DC/DC dual output module" as a new driving method dedicated to creating an intelligent, comfortable, and human-centric lighting environment.
MEAN WELL has recently launched a DALI-2-compliant LCM-40TW intelligent power supply with tunable color temperature and brightness. It can combine with MEAN WELL DLC-02, DALI-2 controller, and DALI-2 input devices (such as touch Panels, presence sensors, and so on) to provide the best solution for indoor intelligent lighting systems. The DALI-2 intelligent lighting configuration schematic is shown in Figure 5.
