The RN5RK from Ricoh Electronic Devices is a DC to DC Converter with Input Voltage 0.7 to 8 V, Output Voltage 1 2 to 5.5 V, Operating Temperature -40 to 85 Degree C, Storage Temperature -55 to 125 Degree C. Tags: Surface Mount, Boost/Step Up. More details for RN5RK can be seen below.