Murata Manufacturing Co Ltd exhibited a digital power supply module for LED lamps at Techno-frontier 2010, a trade show that took place from July 21 to 23, 2010, in Tokyo.
The company used its multi-layer ceramic capacitor (MLCC) for the input and output capacitors of the power supply module. The MLCC can be incorporated in a straight tube-type LED lamp. Compared with an aluminum electrolytic capacitor, the MLCC can make a power supply module smaller and its life longer. It supports the voltages of AC100V and AC200V.
The exhibited digital power supply module was developed for Clear Sodick, a Japan-based LED lighting manufacturer. Murata Manufacturing plans to supply the module to Clear Sodick for the time being, but it is considering selling the module to other companies too. Clear Sodick is selling 20W, 40W and 100W straight tube-type LED lamps, and all of them use the same power supply module, it said.
Murata Manufacturing used a DSP (digital signal processor) microcontroller for constant current control of LED lamps. Its switching frequency is about 200kHz. Two MLCCs with a capacity of about 5μF are used as the output capacitors.
"Normally, this capacity is not enough to absorb ripple current," the company said. "But, by changing the control on the side of the DSP, users do not feel that the lamp is flickering."
The main circuit is a non-isolated buck-boost type and does not have a PFC (power factor correction) circuit. The dimensions are 180 x 19.4 x 6.5mm.
As the DSP microcontroller, Murata Manufacturing employed Microchip Technology Inc's "dsPIC33F GS" and New Japan Radio Co Ltd's "NJU20010 (Alligator)." The latter product was announced in July 2010.
The power supply module equipped with the dsPIC33F GS and the module with the NJU20010 have almost the same main circuit. But the latter module comes with two inductors for a larger output. Clear Sodick plans to use the two types of the modules for different applications.
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