DC-DC LDO is a DC-DC Module with a TO-220 form factor. This is designed to replace existing Linear regulators in use, like LM7805, etc, and is pin-to-pin compatible. The main advantage of using this DC-DC is to reduce the heat generated in the Linear Regulator (LDO) and reduce the size of the design as now you will not need to put a separate heatsink on your board.