The PUC0503S1B from Flex Power Modules is a DC to DC Converter with Input Voltage 4.5 to 5.5 V, Output Voltage 1 3.3 V, Output Current 1 0.3 A, Output Power 1000 mW, Isolation Voltage 6000 Vdc. Tags: Through Hole, Buck/Step down. More details for PUC0503S1B can be seen below.