Integrated Single-Stage Active Power Factor Correction and Isolated Step-Down Controller

ON Semiconductor’s new NCP1651 is an integrated controller that facilitates the simplest possible implementation of power-factor corrected, isolated power converters and reduces both part count and overall design costs for power conversion applications such as battery chargers and distributed power systems up to 200 W.

The NCP1651 provides a low-cost, low component-count solution that is compliant with IEC1000-3-2 harmonic standards for isolated ac-dc converters with mid-high output voltage requirements. Fixed-frequency continuous conduction mode (CCM) operation simplifies the design of the input Electromagnetic Interference (EMI) filter and optimizes efficiency. The controller also can operate in discontinuous conduction mode for maximum design flexibility.

Compared to a conventional power conversion design that uses a PFC controller followed by a dc-dc converter, the unique single-stage design of the NCP1651 eliminates one entire power switching section including the boost inductor, the power MOSFET, the high-voltage capacitor and ancillary components. Unlike other single-stage solutions, the NCP1651 approach reduces the power stage requirements to a minimum: a single magnetic element, a switch, a diode and a capacitor. An internal high-voltage start-up circuit reduces component count further by eliminating external start-up circuitry. Other features of the NCP1651 include a high accuracy multiplier that reduces over-design of the power components, an overtemperature shutdown and an undervoltage lockout.

For more information, visit www.onsemi.com.