The NCP1612 is designed to drive PFC boost stages based on an innovative Current Controlled Frequency Fold−back (CCFF) method. In this mode, the circuit classically operates in Critical conduction Mode (CrM) when the inductor current exceeds a programmable value. When the current is below this preset level, the NCP1612 linearly decays the frequency down to about 20 kHz when the current is null. CCFF maximizes the efficiency at both nominal and light load. In particular, the stand−by losses are reduced to a minimum.

General Features
• Near−Unity Power Factor
• Critical Conduction Mode (CrM)
• Current Controlled Frequency Fold−back (CCFF): Low Frequency Operation is Forced at Low Current Levels
• On−time Modulation to Maintain a Proper Current Shaping in CCFF Mode
• Skip Mode Near the Line Zero Crossing
• Fast Line / Load Transient Compensation (Dynamic Response Enhancer)
• Valley Turn On
• High Drive Capability: −500 mA/+800 mA
• VCC Range: from 9.5 V to 35 V
• Low Start−up Consumption
• A Version: Low VCC Start−up Level (10.5 V), B Version: High VCC Start−up Level (17.0 V)
• Line Range Detection
• pfcOK Signal
• This is a Pb−Free Device

Safety Features
• Separate Pin for Fast Over−Voltage Protection (FOVP) and Bulk Under−Voltage Detection (BUV)
• Soft Over−Voltage Protection
• Brown−Out Detection
• Soft−Start for Smooth Start−up Operation (A version)
• Over Current Limitation
• Disable Protection if the Feedback and FOVP/BUV pins are not connected
• Thermal Shutdown
• Latched Off Capability
• Low Duty−Cycle Operation if the Bypass Diode is shorted
• Open Ground Pin Fault Monitoring

Typical Applications
• PC Power Supplies
• All Off Line Appliances Requiring Power Factor Correction