The NCP1611 is active power factor corrected (PFC) controller specifically designed for use as a boost preconverter 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 NCP1611 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.
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Critical Conduction mode with current controlled frequency foldback
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Optimizes conversion efficiency across load range
Dynamic Response Enhancer
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Improved transient response for line and load steps
Soft Overvoltage Protection (S-OVP)
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Reduces accoustic noise and stress in the even of an overvoltage fault
-500 mA/+800 mA Drive Capability
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High drive to support wide range of FETS and power levels
Valley Turn On
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Improved efficiency and reduced EMI generation
Wide Vcc Range of 9.5-35V
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Easy to Bias even at light load and high line conditions
Two Vcc Startup Versions: 10.5V (A) and 17V (B)
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B version allows smaller Vcc capacitor and faster startup in self biased applications
AC Line Brownout Detection
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Protect boost stage from fault conditions
Saturated Inductor and shorted boost or bypass protection
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Enhances safe operating monitoring without extra components
