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To prevent the output white light from being experienced with color deviation due to temperature effect on the performance of light-emitting diode (LED), a mixed-light control module is developed, by integrating Programmable System on Chip (PSoC) with photo-diode sensor devices, to examine the ambient temperature and feedback voltage level of RGB photodiodes. Also, a mixing light color criterion of RGB LED is applied on the mixed-light control module. Through the usage of mixing light color criterion of RGB LED, the corresponding duty cycle of RGB LED can be adjusted, and the stable white light output can, consequently, be achieved. By the feedback compensation of mixed-light control module the CIE1931 xy coordinates of output light are in good agreement with the predicted results.

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