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 NCP1341 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 NCP1341 enters quiet−skip
mode to manage the power delivery while minimizing acoustic noise.
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 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
• 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)
• Fixed or Adjustable Maximum Frequency Clamp
• Fault Pin for Severe Fault Conditions, NTC Compatible for OTP
(9−Pin Version Only)
• 4 ms Soft−Start Timer