LED lamp color temperature intelligent controller application program

January 11, 2020

[Source: "High - tech LED - Technology and Applications" November issue ]

LED lighting applications have strict requirements on the four interfaces of opto-mechanical heat, and they affect each other and restrict each other. The following is a brief introduction to the design of an intelligent LED lamp controller that automatically adjusts the color temperature of the LED as the ambient temperature changes.

Studies have shown that color temperature affects people's mood and feelings. The higher the color temperature, the colder the feeling is. The lower the color temperature, the warmer the feeling. For example, on a cold night, when the color temperature of the light is 6500K, people will feel colder, and when the color temperature of the light is 2700K, people will feel warmer. With the improvement of the quality of life, people hope that the color temperature of LED lights can be automatically adjusted with the change of ambient temperature to further improve people's quality of life. The color temperature of current LED lamps is generally fixed and cannot be automatically adjusted according to changes in ambient temperature. For this article, we will introduce a smart LED lamp controller solution that automatically adjusts the LED color temperature as the ambient temperature changes. The scheme is mainly composed of three parts: (1) NTC negative temperature coefficient thermistor; (2) STC 1 2 C 5 4 0 4 AD microcontroller intelligent control unit; (3) PT4115 constant current module;

Its working principle and schematic diagram are shown in Figure 1:


Working principle: The single-chip STC12C5404AD collects the temperature sensing parameters of NTC in real time, judges the temperature change of the current environment according to this parameter, and outputs PWM pulse signals with different duty cycles to control the output of different currents of PT4115 constant current module, different current driving Light bulbs of different color temperatures will change in brightness, and after mixing, light of corresponding color temperature will be formed. Therefore, the LED lamp controller can control the color temperature of the light to be automatically adjusted as the ambient temperature changes.

The LED lamp controller scheme will be further described below in conjunction with a specific example.

Simple sample of the program (Figure 2, Figure 3):

First, set the temperature range of adjustment to 10 ° C ~ 35 ° C;

Second, the color temperature of the LED lamps in the corresponding temperature range is as follows (Ta: temperature):

Ta<10°C --3000K

10°C≤Ta<25°C --4000K

25°C≤Ta<35°C --5000K

35°C≤Ta --6000K


Third, the STC12C5404AD MCU controls two LED lamp beads through two PT4115 constant current drive modules; the full drive current of two PT4115 constant current drive modules (respectively recorded as the first PT4115 constant current drive module and the second PT4115 constant current drive module) Both are 340mA; the color temperature of the two LED lamp beads are 3000K and 6000K respectively (remembered as the first LED lamp bead 3000K and the second LED lamp bead 6000K, respectively, and the first PT4115 constant current drive module and the second PT4115 constant current respectively Drive module control) as shown in Figure 3 LED module.

Fourth, the duty cycle of the PWM control signal output by the STC1 2C5 4 0 4AD microcontroller and the current output by the first PT4115 constant current driving module, the second PT4115 constant current driving module, and the first LED lamp bead 3000K, the second LED The color temperature of the LED luminaires that will be formed after the lamp 6000K lights are mixed is as shown above (Table 1).


Unfinished

For more information, please refer to "High - tech LED - Technology and Applications" November issue

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