QUASI−RESONANT PWM CONTROLLER FOR HIGH POWER AC−DC WALL ADAPTERS

The NCP1380 hosts a high−performance circuitry aimed to powering quasi−resonant converters. Capitalizing on a proprietary valley−lockout system, the controller shifts gears and reduces the switching frequency as the power loading becomes lighter. This results in a stable operation despite switching events always occurring in the drain−source valley. This system works down to the 4th valley and toggles to a variable frequency mode beyond, ensuring an excellent standby power performance.

FEATUREs
•Quasi−Resonant Peak Current−Mode Control Operation
•Valley Switching Operation with Valley−Lockout for Noise−Immune Operation
•Frequency Foldback at Light Load to Improve the Light Load Efficiency
•Adjustable Over Power Protection
•Auto−Recovery or Latched Internal Output Short−Circuit Protection
•Fixed Internal 80 ms Timer for Short−Circuit Protection
•Combined Overvoltage and Overtemperature Protection (A and B Versions)
•Combined Overvoltage Protection and Brown−Out (C and D Versions)
•+500 mA / −800 mA Peak Current Source/Sink Capability
•Internal Temperature Shutdown
•Direct Optocoupler Connection
•Extended VCCRange Operation Up to 28 V
•Extremely Low No−Load Standby Power
•SO−8 Package
•These Devices are Pb−Free and are RoHS Compliant

Typical Applications
•High Power ac−dc Converters for TVs, Set−Top Boxes etc.
•Offline Adapters for Notebooks