Enhanced, High-Efficiency Power Factor Controller

The NCP1611 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 NCP1611 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.

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
• This is a Pb−Free Device

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