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.

To improve the safety in overload situations, the controller includes

an Over Power Protection (OPP) circuit which clamps the delivered

power at high−line. Safety−wise, a fixed internal timer relies on the

feedback voltage to detect a fault. Once the timer elapses, the

controller stops and stays latched for option A and C or enters

auto−recovery mode for option B and D.

Particularly well suited for adapter applications, the controller

features a pin to implement either a combined overvoltage /

overtemperature protection (Version A and B) or a combined

brown−out/overvoltage protection (Version C and D).

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 VCC Range 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