A constant voltage controlled LED packaging module with a temperature compensating capacitor

Abstract

Due to the thermal energy affects on the electrical property of LED, its driving power requires constant current control to adjust brightness. However, this approach requires extensive electronic parts to conduct signal processing, which will decrease the reliability and lifetime of LED. Moreover, as the packaging volume increases, manufacturing costs become relatively higher. In order to address these issues, a silicon-based LED packaging module with a temperature compensating capacitor is proposed, which can provide stable luminous efficiency, and be applied to the constant voltage driving mode. The packaging module uses 3D stacking technology to integrate LED and a capacitor on a silicon micromachining substrate. The inductor is used for electrical impedance with a capacitor when supplying a constant voltage with periodical switch mode to LED. Based on this configuration, the temperature variation generated by the LED can directly change the capacitance in a series driving circuit; thereby, compensating the resistance variation in the LED to stabilize the driving current. Thus, a miniaturized, low-cost, constant voltage controllable LED module can be achieved.