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NCP1611 Generator Frequency Calculator Excel Spreadsheet

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NCP1611 Generator Frequency Calculator Excel Spreadsheet

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Description #1:

The NCP1611 is designed to drive PFC boost stages in so-called Current Controlled Frequency Fold-back (CCFF). 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.

Like in FCCrM controllers, an internal circuitry allows near-unity power factor even when the switching frequency is reduced. Housed in a SO-8 package, the circuit also incorporates the features necessary for robust and compact PFC stages, with few external components. In particular, the stand-by losses are reduced to a minimum.

This Excel spreadsheet helps designing a 1-phase PFC stage based on the NCP1611 by computing the main external components (refer to the generic application schematic of this sheet). The calculations are based on the equations and process detailed in the application note AND9062/D.

As for the brown-out circuitry, the tool proposes two options: - one where the line voltage is directly used (recommended, particularly when resistors are implemented to discharge the X2 capacitors) - the classical one where the rectified line voltage is sensed.

Description #2

Enhanced, High Efficiency PFC Controller

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.