DER-114 - 21 W backup power supply

This engineering report describes a universal input 5 V, 4 A power supply designed around the TNY280P device of the TinySwitch-III IC family. Although designed as a auxiliary or bias supply for personal computer (PC) power supplies, the design can also be used as a general-purpose evaluation platform for TinySwitch-III devices. Typically, PC power supplies have a power factor correction (PFC) input stage. However, since the bias supply must operate before the PFC stage is activated, this supply is designed for general-purpose input operation. For evaluation purposes, input rectification and input storage capacitance have been included. In real applications, this stage and EMI filter components are usually part of the main PC power supply. The report contains power supply specifications, circuit diagrams, complete bill of materials (BOM), PI Xls transformer spreadsheet design results, complete transformer documentation, printed circuit board (PCB) layout and related performance data.