Current limiting diode (CLD) was fabricated using junction field effect transistor (JFET) structured two small cells and eight large cells. Two small cells and eight large cells were connected in parallel and the obtained constant current was 110 mA. The application of CLD in each of the parallel circuits on chip on board (COB) type LED lighting source, could significantly reduce the current deviation within the parallel circuits. The applications of CLD on AC power small lighting source, battery power low voltage parallel lighting source and AC flat lighting source were investigated.

In this paper, by designing 20 W class driving circuit for driving high-power LED (Light Emitting Diode), we are going to comparatively carry out the analysis of characteristics for power circuit according to each design method. In this case, 200 V 60 Hz was performed as input data. The electrical characteristics such as voltage, current and ripple are checked for constant current circuit and constant voltage circuit in the LED module. In addition, as the ripple has an influence on illumination of LED light, low temperature working (-20 [℃]) and high temperature working(80 [℃]) are measured to make sure the ripple characteristics in accordance with temperature. In low temperature operation -20 [℃] measurements, both constant current circuit and constant-voltage circuit were less impacted on input fluctuation, whereas in the high temperature operation 80 [℃], current voltage in constant voltage circuit was surge after 430 [hour]. Voltage current ripple of constant current circuit was much less than constant voltage circuit, therefore we can show that constant current circuit is more stable.

This paper presents the design and reliability evaluation of metallized film capacitor for power electronics application. The rated voltage of development capacitor is DC 3300[V], the capacitance is 5 μF and the ripple current capability is 130 A(rms). Film metallization and patterns are an important design factor that has been development enhance the electric and reliability properties of film capacitor for power electro nics. In term of capacitor construction and metallized pattern is one of the parameters that can be modified to further improve the rating in the terms of maximum ripple current and lifetime. This capacitor can be used as snubber capacitor application such as power train invertor system.