Product Overview NCP1249: PWM Controller Featuring Peak Power Excursion and HV Startup For complete documentation, see the data sheet Product Description The NCP1249 is a highly integrated high-voltage PWM controller capable of delivering a rugged and high performance offline power supply with extremely low no-load consumption. With a supply range up to 30 V, the controller hosts a jittered 65-kHz switching circuitry operated in peak current mode control. When the power on the secondary side starts to decrease, the controller automatically folds back its switching frequency down to a minimum level of 26 kHz. As the power further goes down, the part enters skip cycle while freezing the peak current setpoint. To help build rugged converters, the controller features several key protective features: an internal brown-out, a non-dissipative Over Power Protection for a constant maximum output current regardless of the input voltage and two latched over voltage protection inputs - either through a dedicated pin or via the Vcc input. The controller architecture is arranged to authorize a transient peak power excursion when the peak current hits the limit. At this point, the switching frequency is increased from 65 kHz to 130 kHz until the peak requirement disappears. The timer duration is then modulated as the converter crosses a peak power excursion mode (long) or undergoes a short circuit (short). Similar to NCP1255 & NCP1254 with integrated HV Startup NCP1249 has Active ON (A&B) and Active OFF (C&D) versions. Features Benefits • Integrated High Voltage startup • 65kHz operating frequency with 130kHz Frequency Excursion • Internal and Adjustable Over Power Protection (OPP) Circuit • Adjustable Brown-Out Protection • Frequency Foldback down to 26 kHz and Skip-cycle in light load conditions • Adjustable Timer-based Auto-recovery Overload/Short-circuit protection with 100% to 25% timer reduction for short-circuit faults • Frequency Jittering in Normal and Frequency Foldback Modes • Latch Input • Double Vcc hiccup in fault mode Applications • Provides lossless start-up sequence • Allows for a high peak power delivery without increasing the transformer size • Compensates peak current for changing line conditions • Protects against drops in AC line input voltage • Optimized efficiency across the entire power range • Robust protection against both overload and short circuit conditions • Softened EMI signature • Flexible input can be used for OVP or OTP protection • Reduced average power during fault mode End Products • Ac-Dc Adapters • Notebook Adapters • Printer Power Supplies Part Electrical Specifications Product Compliance Status Topolog y Control Mode fsw Typ (kHz) StandUVLO by Mode (V) Short Circuit Protecti on Latch Soft Start VCC Max Drive (V) Cap. (mA) Packag e Type NCP1249AD65R2G Pb-free Active Flyback Current Mode 65 Yes 8.8 Yes Yes Yes 35 300 / 500 SOIC9 NB Active Flyback Current Mode 65 Yes 8.8 Yes Yes Yes 35 300 / 500 SOIC9 NB Active Flyback Current Mode 65 Yes 8.8 Yes Yes Yes 35 300 / 500 SOIC9 NB Active Flyback Current Mode 65 Yes 8.8 Yes Yes Yes 35 300 / 500 SOIC9 NB Halide free NCP1249BD65R2G Pb-free Halide free NCP1249CD65R2G Pb-free Halide free NCP1249DD65R2G Pb-free Halide free Application Diagram For more information please contact your local sales support at www.onsemi.com Created on: 6/30/2016