Quasi-Resonant Current-Mode Controller for High-Power Universal Off-line Supplies

The NCP1379 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 Output Short−Circuit Protection
• Fixed Internal 80 ms Timer for Short−Circuit Protection
• Combined Overvoltage Protection and Brown−out
• +500 mA / −800 mA Peak Current Source/Sink Capability
• Internal Temperature Shutdown
• Direct Optocoupler Connection
• Low VCC(on) Allowing to Use a Standby Power Supply to Power the Device
• Extremely Low No−Load Standby Power
• SO8 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