A dc-dc regulator/converter or another name known as buck regulator, provides stable regulated output voltage to supply electronic circuits. Schematic, PCB layout and component list are available on this page.
LM2576 circuits perform same function as the commonly known voltage regulator LM7805 from National Semiconductor. The 7805 voltage regulator dissipates a lot heat. The higher input voltage, the more heat is generated. The extra input energy is converted to heat, keeping the output voltage regulated at 5V.
DC-DC converter using LM2576 - [Link]