Japan Developed LED Lighting Power without Electrolytic Capacitors

Murata Manufacturing Co., Ltd. displayed the digital power circuit for LED lighting at "TECHNO FRONTIER 2010 (Power System Exhibition)," which opened on July 21, 2010. The company's laminated ceramic capacitors (MLCC) are used as input and output capacitors and can be built into the tubes of straight-tube LED lighting fixtures. Compared with the use of aluminum electrolytic capacitors, in addition to reducing the size of the product, but also extend the product life. The input voltage supports AC100V and 200V.

The power module developed by Murata Manufacturing Co., Ltd. for LED lighting manufacturer Clear Sodick was displayed this time. It is currently only available for Clear Sodick but is also considering selling to other companies. Clear Sodick is a direct-piped LED lighting business that equates to 20W, 40W, and 100W fluorescent lamps. The power modules for all types of products are universal.

In order to obtain a constant current for LED lighting, a DSP microcontroller is used. Switching frequency is about 200kHz. The output capacitor uses two MLCCs of about 5 μF. "In general, the MLCC of this capacity cannot fully absorb the pulsating current, but by improving the control of the DSP side, it does not feel the flickering of the lighting fixture" (Murata Manufacturing Co., Ltd.). The main circuit uses a non-insulated buck-boost type and does not have a PFC (power factor improvement) circuit. Dimensions are 180mm x 19.4mm x 6.5mm

DSP microcontrollers are available from Microchip Technology's "dsPIC33F GS Series" and Nippon Wireless' NJU20010 (Alligator Series). The latter is just released by New Japan Wireless in July 2010. The main circuit of all power supply modules is almost universal, but the power supply module using the Nippon Wireless DSP microcontroller adds two inductors for higher output power. Clear Sodick is scheduled to use these two types of power modules.