Housed in a SO--14 package, the NCP1381/82 includes everything

needed to build rugged and efficient Quasi--Resonant (QR) Switching

Power Supplies. When powered by a front--end Power Factor

Correction circuitry, the NCP1381/82 automatically disconnects the

PFC controller in low output loading conditions (with an adjustable

level), thus improving the standby power. This is particularly well

suited for medium to high power offline applications, e.g. notebook

adapters.When the current setpoint falls below a given value, e.g. the

output power demand diminishes, the IC automatically enters the

so--called skip cycle mode and provides excellent efficiency at light

loads. Because this occurs at an adjustable low peak current together

with a proprietary Soft--Skipt technique, no acoustic noise takes

place. Skip cycle also offers the ability to easily select the maximum

switching frequency at which foldback and standby take place.

The NCP1381/82 also features several efficient protection options

like a) a short--circuit / overload detection independent of the auxiliary

voltage b) an auto--recovery brown--out detection and c) an input to

externally latch the circuit in case of Overvoltage Protection or Over

Temperature Protection.

Features

 Current--Mode Quasi--Resonant Operation

 Adjustable Line Over Power Protection

 Extremely Low Startup Current of 15 mAMaximum

 Soft--Skip Cycle Capability at Adjustable Peak Currents

 Plateau Sensing Overvoltage

 Brown--Out Protection

 Maximum tON Limitation

 Overpower Protection by current Sense Offset

 Internal 5 ms Soft--Start Management

 Short--Circuit Protection Independent from Auxiliary Level

 External Latch Input Pin for an OTP Signal

 Go--To--Standby Signal for the PFC Front Stage

 True Frequency (tON + tOFF) Clamp Circuit

 Low and Noiseless, No--Load Standby Power

 Internal Leading Edge Blanking

 +500 mA / --800 mA Peak Current Drive Capability

 5 V / 10 mA Reference Voltage

 These are Pb--Free Devices

Typical Applications

 High Power AC/DC Adapters for Notebooks, etc

 Offline Battery Chargers

 Set--Top Boxes Power Supplies, TV, Monitors, etc