The NCP1345 is a highly integrated quasi−resonant flyback
controller suitable for designing high−performance off−line USB−PD
and USB Type−C power converters. The included dual−pin VCC
architecture allows direct connection to the aux winding for simplified
VCC management with a reduced parts count and increased
performance.
The NCP1345 also features a precise, primary side based output
current limiting circuit to ensure a constant output current limit
regardless of programmed output voltage, or nameplate output power.
The quasi−resonant (QR) current−mode flyback stage features
proprietary valley−lockout circuitry to ensure stable valley switching
down to the 6th valley, then transitions to frequency foldback mode to
reduce switching losses. As the load decreases further, the NCP1345
enters skip mode to manage the power delivery.
To help ensure converter ruggedness, the NCP1345 implements
several key protective features such as internal brownout detection, a
maximum output current limit regardless of input voltage, a latched
over voltage and NTC−ready overtemperature protection through a
dedicated pin, and line removal detection to safely discharge the X2
capacitors when the line is removed.

Features
• Integrated High−Voltage Startup Circuit with Brownout Detection
• Integrated X2 Capacitor Discharge Capability
• Wide VCCL Range from 8 V to 38 V
• 150 V VCCH Pin for Connection to High−Voltage Aux Winding
• 36.5 V VCC Overvoltage Protection
• Primary Side Based Constant Output Current Limiting
• Abnormal Overcurrent Fault Protection for Winding Short Circuit
Detection
• Internal Temperature Shutdown
• Valley Switching Operation with Valley−Lockout for Noise−Free
Operation
• Rapid Frequency Foldback for Fast Reduction of Switching
Frequency
• Skip Mode with Output Voltage Compensation
• Minimized No Load Power Consumption
• Frequency Jittering for Reduced EMI Signature
• Latching or Auto−Recovery Overload Protection
• Adjustable Overpower Protection
• Fixed/Adjustable Maximum Frequency Clamp
• Fault Pin for Severe Fault Conditions, NTC Compatible for OTP