In this case, DC DC switching regulator has 1 outputs configured to it. DC DC switching regulators like this one generate Fixed outputs on their output pins to handle the power management. It has a 4-pin voltage regulator dc to dc.
REZ-243.3S Features
1 outputs
REZ-243.3S Applications
There are a lot of RECOM Power REZ-243.3S Voltage Regulators applications.