This application note presents a design guideline for a single-stage flyback AC-DC converter using FL6961 for LED lighting applications. It focuses on how to select and design the flyback transformer for a 16.8W (24V/0.7A) solution for universal input. The flyback converter using FL6961 operates in Critical Conduction Mode (CRM) and has functions such as CC/CV feedback circuit, soft-starting, and cycle-by-cycle current limit for LED lighting applications.