R1800K Series DC/DC Converters Nisshinbo R1800K Series DC/DC Converters are power-storing buck DC/DC converters for photovoltaic and vibration energy harvesters. A low operating quiescent current allows a harvester to be used under a low-illumination environment. The R1800K series delivers high efficiency of approximately 90% at 10μA. Nisshinbo R1800K Series DC/DC Converters are suitable for equipment with low power supplied by a harvester.