The PUA0503S1A 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 2000 Vdc. Tags: Through Hole, Buck/Step down. More details for PUA0503S1A can be seen below.