onsemi NCP1341B4D1R2G

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.

The NCP1341 implements a quasi−resonant flyback converter utilizing current−mode architecture where the switch−off event is dictated by the peak current. This IC is an ideal candidate where low parts count and cost effectiveness are the key parameters, particularly in ac−dc adapters, open−frame power supplies, etc. The NCP1341 incorporates all the necessary components normally needed in modern power supply designs, bringing several enhancements.

• 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