The NCP1612 is active power factor corrected (PFC) controller specifically designed for use as a boost pre-converter in ac-dc adapters, flat TVs, lighting ballasts and other medium powered offline applications. The controller is based on an innovative Current Controlled Frequency Foldback(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 reduces the frequency down to about 20 kHz when the current is at a null. CCFF maximizes the efficiency at both nominal and light load. In particular, the standby losses are reduced to a minimum. The controller features a robust suite of protection features to properly handle an array of power supply operating and fault conditions.This device is particularly suited a PFC stage for LLC controllers due to its dedicated PFC_Okay Output.

• Critical conduction mode with current controlled frequency foldback
• Dynamic Response Enhancer
• Soft Overvoltage Protection
• -500 mA/+800 mA Drive Capability
• Valley turn on
• Wide Vcc Range of 9.5-35 Vdc
• Two Vcc startup versions: 10.5 V (A) and 17 V (B)
• AC Line Brownout Detection
• Cycle-by-cycle switch current monitoring
• Saturated inductor and shorted boost or bypass diode detection
• PFC Okay Output
• Latch Off Input
• Independent bulk overvoltage and undervoltage monitoring
• Open Ground Pin Fault Monitoring
• Near Unity Power Factor
• Thermal Shutdown