The MC33368 is an active power factor controller that functions as a boost preconverter in off−line power supply applications. MC33368 is optimized for low power, high density power supplies requiring a minimum board area, reduced component count and low power dissipation. The narrow body SOIC package provides a small footprint. Integration of the high voltage startup saves approximately 0.7 W of power compared to resistor bootstrapped circuits.

The MC33368 features a watchdog timer to initiate output switching, a one quadrant multiplier to force the line current to follow the instantaneous line voltage a zero current detector to ensure critical conduction operation, a transconductance error amplifier, a current sensing comparator, a 5.0 V reference, an undervoltage lockout (UVLO) circuit which monitors the VCC supply voltage and a CMOS driver for driving MOSFETs. The MC33368 also includes a programmable output switching frequency clamp. Protection features include an output overvoltage comparator to minimize overshoot, a restart delay timer and cycle−by−cycle current limiting.

Features

• Lossless Off−Line Startup

• Output Overvoltage Comparator

• Leading Edge Blanking (LEB) for Noise Immunity

• Watchdog Timer to Initiate Switching

• Restart Delay Timer

• Pb−Free Packages are Available*