NCP1339JDR2G

The NCP1339JDR2G from ON Semiconductor is a highly integrated quasi-resonant flyback controller. It is designed to control rugged and high-performance off-line power supplies, making it suitable for adapter applications. With an integrated active X-cap discharge feature and a power saving mode, this controller can enable no-load power consumption below 10 mW for 45 W notebook adapters.

The quasi-resonant current-mode flyback stage incorporates proprietary valley-lockout circuitry for stable valley switching. The system operates down to the 6th valley and toggles to a frequency foldback mode to eliminate switching losses. When the loop forces frequencies below 25 kHz, the NCP1339 skips cycles to manage power delivery.

For building rugged converters, the NCP1339JDR2G includes several protective features: internal brown-out detection, non-dissipative Over Power Protection for constant maximum output current regardless of input voltage, and latched over-voltage protection. It operates within a wide VCC range of 10 V to 28 V and features abnormal overcurrent fault protection for winding short circuit or inductor saturation detection. The device is available in a 14-SOIC package and operates at temperatures from -40°C to 125°C (TJ).

Key features include a high-voltage current source for lossless start-up, X2 capacitor discharge capability, and internal temperature shutdown. It also supports frequency fold-back for high performance in standby mode and a 25-kHz clamp and skip mode. The controller has an adjustable overpower protection and a 4 ms soft-start timer.