The NCP1345, manufactured by onsemi, is a highly integrated quasi-resonant flyback controller optimized for high-performance off-line USB-PD and USB Type-C power converters. This advanced controller features a dual-pin Vcc architecture for simplified Vcc management and enhanced performance, allowing direct connection to the auxiliary winding. It incorporates a precise primary side-based output current limiting circuit to ensure a constant output current limit irrespective of the programmed output voltage or nameplate output power. The quasi-resonant (QR) current-mode flyback stage is equipped with proprietary valley-lockout circuitry for stable valley switching down to the 6th valley and transitions to frequency foldback mode to reduce switching losses. Additional load decreases trigger the NCP1345 to enter skip mode for efficient power management. Key protective features include internal brownout detection, maximum output current limit, latched overvoltage, and NTC-ready overtemperature protection, as well as line removal detection for safe discharge of X2 capacitors. The NCP1345 is available in SOIC-9 NB packages and supports various configurations and protection mechanisms, making it a robust solution for modern power supply designs.