The BD9B400MUV from ROHM Semiconductor is a DC to DC Converter with Input Voltage 2.7 to 5.5 V, Output Voltage 1 0.8 to 4.4 V, Output Current 1 4000 mA, Operating Temperature -40 to 85 Degree C, Storage Temperature -55 to 150 Degree C. Tags: Surface Mount, Buck/Step down. More details for BD9B400MUV can be seen below.