The NCP1342 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 NCP1342 can enable no−load power consumption below 30 mW.
The NCP1342 features a proprietary valley−lockout circuitry,
ensuring stable valley switching. This system works down to the 6th
valley and transitions to frequency foldback mode to reduce switching
losses. As the load decreases further, the NCP1342 enters quiet−skip
mode to manage the power delivery while minimizing acoustic noise.
To ensure light load performance with high frequency designs, the
NCP1342 incorporates Rapid Frequency Foldback with Minimum
Peak Current Modulation to reduce the switching frequency quickly.
To help ensure converter ruggedness, the NCP1342 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 overvoltage and
NTC−ready overtemperature protection through a dedicated pin, and
line removal detection to safely discharge the X2 capacitors when the
ac line is removed.

Features
• Integrated High−Voltage Startup 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 Foldback with 25 kHz Minimum Frequency Clamp for
Increased Efficiency at Light Loads
• Rapid Frequency Foldback for Fast Reduction of Switching
Frequency at Light Loads
• Skip Mode with Quiet−Skip Technology for Highest Performance
During Light Loads
• Minimized Current Consumption for No Load Power Below 30 mW
• Frequency Jittering for Reduced EMI Signature
• Latching or Auto−Recovery Timer−Based Overload Protection
• Adjustable Overpower Protection (OPP)
• Adjustable Maximum Frequency Clamp
• Fault Pin for Severe Fault Conditions, NTC Compatible for OTP
• 4 ms Soft−Start Timer