The ON Semiconductor series NCP1343 is a highly integrated quasi−resonant fly back controller suitable for designing high−performance off−line power converters. The NCP1343 features a proprietary valley−lockout circuitry, ensuring stable valley switching. This system works down to the 6th valley and transitions to frequency fold back mode to reduce switching losses. As the load decreases further, the NCP1343 enters quiet−skip mode to manage the power delivery while minimizing acoustic noise.

Integrated High−Voltage Start-up Circuit with Brownout Detection
Integrated X2 Capacitor Discharge Capability
Wide VCC Range from 9 V to 28 V
28 V VCC Overvoltage Protection
Abnormal Overcurrent Fault Protection for Winding Short Circuit or Saturation Detection
Internal Temperature Shutdown
Valley Switching Operation with Valley−Lockout for Noise−Free Operation
Frequency Fold back with 25 kHz Minimum Frequency Clamp for Increased Efficiency at Light Loads