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
• Six Versions: NCP1612A, B, A1, A2, A3 and B2 (see Table 1)
• Line Range Detection
• pfcOK Signal
• This is a Pb-Free Device

Safety Features
• Separate Pin for Fast Over-voltage Protection (FOVP) for Redundancy
• Soft Over-voltage Protection
• Brown-out Detection
• Soft-start for Smooth Start-up Operation (A, A1, A2 and A3 Versions)
• Over Current Limitation
• Disable Protection if the Feedback is Not Connected
• Thermal Shutdown
• Latched Off Capability
• Low Duty-cycle Operation if the Bypass Diode is shorted
• Open Ground Pin Fault Monitoring
• Saturated Inductor Protection
• Detailed Safety Testing Analysis (Refer to Application Note AND9079/D)

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