The LTM4639 from Analog Devices is a DC to DC Converter with Input Voltage 2.375 to 7 V, Output Voltage 1 0.6 V, Output Current 1 20000 mA, Operating Temperature -40 to 125 Degree C, Storage Temperature -55 to 125 Degree C. Tags: Surface Mount, Buck/Step down. More details for LTM4639 can be seen below.