45 W Flyback converter with lossless zero crossing circuit

This report describes a universal input, 19 V, 45 W isolated flyback converter employing LNK6777E from the LinkSwitch-HP family of ICs. It contains the complete specification of the power supply, a detailed circuit diagram, the entire bill of materials required to build the supply, extensive documentation of the power transformer, along with test data and waveform plots of the most important electrical waveforms.

The most significant aspect of this design is to demonstrate implementing secondary side optocoupler feedback with LinkSwitch-HP devices.

Typical LinkSwitch-HP designs are primary side regulated however the addition of optocoupler feedback allows the part to address applications with both stringent transient response (0 to 100%) and no-load input power (