DER-617 - 8.4 W high power factor, isolated flyback LED driver

This engineering report describes a constant voltage (CV) output 8.4 W isolated flyback power supply with single-stage power factor correction circuit for smart lighting applications. This power supply is designed to provide a constant 24 V voltage on a 0mA to 350 mA output current load. The board is optimized to operate over an input voltage range of 90 VAC to 265 VAC. The LYTSwitch-6 IC combines primary, secondary and feedback circuits in a surface mount, offline flyback switch IC. It contains the primary MOSFET, primary side controller and secondary side synchronous rectification controller. The device also features innovative FluxLink™ technology that safely bridges the isolation barrier without the need for an optocoupler. Adding a single stage power factor correction circuit can meet the high PF requirements in lighting applications. This topology is similar to a boost topology in that the power switch is shared with an isolated flyback converter. The energy stored on the PFC inductor is transferred to the load via direct energy transfer, thereby reducing power losses. The DER-617 uses a LYTSwitch-6 IC to provide accurate, fast transient response, constant voltage power supply, and high power factor over the entire input range. The key design goals are to achieve high efficiency and high power factor over the entire input voltage range. This document contains power supply specifications, schematics, bill of materials, transformer documentation, printed circuit layout and performance data.