资 源 简 介
The MC33368 is an acTIve power factor controller that funcTIons as aboost preconverter in off−line power supply applicaTIons. MC33368 isopTImized for low power, high density power supplies requiring aminimum board area, reduced component count and low powerdissipation. The narrow body SOIC package provides a smallfootprint. Integration of the high voltage startup saves approximately0.7 W of power compared to resistor bootstrapped circuits.The MC33368 features a watchdog timer to initiate outputswitching, a one quadrant multiplier to force the line current to followthe instantaneous line voltage a zero current detector to ensure criticalconduction operation, a transconductance error amplifier, a currentsensing comparator, a 5.0 V reference, an undervoltage lockout(UVLO) circuit which monitors the VCC supply voltage and a CMOSdriver for driving MOSFETs. The MC33368 also includes aprogrammable output switching frequency clamp. Protection featuresinclude an output overvoltage comparator to minimize overshoot, arestart 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*
