DER-228 - 15 W power supply

This report describes a universal input 12 V, 1.25 A flyback power supply using the TNY278P device from the TinySwitch-III family of ICs. The goal of this design is to demonstrate the extremely low no-load input power achievable with TinySwitch-III devices. The design is based on the EP91 reference design board. The only changes are to optimize the bias winding component that provides operating current to the BYPASS pin of the TNY278P IC and to change the output diode from PN ultrafast to Schottky barrier type. The report contains complete specifications of the power supply, detailed circuit diagrams, a complete list of materials required to build the power supply, extensive documentation of the power transformer, and test data and oscilloscopes of the most important electrical waveforms. This board offers many user-configurable options and is designed to showcase the capabilities and flexibility of the TinySwitch-III family. These include easy adjustment of the device current limit to increase output power or improve operating efficiency, as well as latching output overvoltage shutdown.