NCP1341: Quasi-Resonant Controller, High-Voltage, Featuring Valley Lock-Out Switching with Power Excursion Mode (PEM)

The NCP1341 is a highly integrated quasi−resonant flyback controller suitable for designing high−performance off−line power converters. With an integrated active X2 capacitor discharge feature, the NCP1341 can enable no−load power consumption below 30 mW. The quasi−resonant current−mode flyback stage features a proprietary valley−lockout circuitry, ensuring stable valley switching. This system works down to the 6th valley and transitions to a frequency foldback mode to reduce switching losses. As the load decreases further, the NCP1341 enters quiet−skip mode to manage the power delivery. The NCP1341 integrates power excursion mode (PEM) to minimize transformer size in designs requiring high transient load capability. If transient load capability is not desired, the NCP1340 offers the same performance and features without PEM. To help ensure converter ruggedness, the NCP1341 implements several key protective features such as internal brownout detection, a non−dissipative Over Power Protection (OPP) for constant maximum output power regardless of input voltage, a latched over voltage and NTC−ready over-temperature protection through a dedicated pin, and line removal detection to safely discharge the X2 capacitors when the line is removed.