onsemi NCP1342 Quasi-Resonant Flyback Controllers

onsemi NCP1342 Quasi-Resonant Flyback Controllers are highly integrated High-Frequency PWM (Pulse Width Modulation) Controllers intended to simplify the design of high-performance off-line power converters. With an integrated active X2 capacitor-discharge feature, the NCP1342 devices enable no-load power consumption below 30mW.

The NCP1342 features 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 Minimum Peak Current Modulation (MPCM) to reduce the switching frequency quickly. To help ensure converter ruggedness, the NCP1342 implements several key protective features such as internal brownout detection, non-dissipative Over Power Protection (OPP) for constant maximum output power regardless of input voltage, a latched overvoltage, 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 NCP1342 is offered in SOIC-8 and SOIC-9 packages for design flexibility.

Features

Integrated high-voltage startup circuit with brownout detection
Integrated X2 capacitor-discharge capability
Wide V_CC range from 9V to 28V
28V V_CC 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 25kHz 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 the highest performance during light loads