ON Semiconductor Introduces Integrated Power Factor Controller

ON Semiconductor has introduced the NCP1901, an integrated circuit that combines both a power factor correction (PFC) controller and a resonant half-bridge controller in a single package. The high level of integration of the NCP1901 permits off-line adapters to be designed with minimal form factor while meeting worldwide efficiency standards, such as ENERGY STAR v2.0 for external power supplies, California Energy Commission (CEC), European Code of Conduct and China Standard Certification Center (CSC).

The advantage of the NCP1901 is the unique combination of a PFC controller operating in a critical conduction mode (CRM) and a resonant half-bridge controller. Overall voltage regulation is maintained by adjusting the PFC output voltage. This allows a fixed frequency resonant controller to be utilized, reducing the transformer size and maximizing efficiency.

With ON Semiconductor’s proprietary high voltage technology, the NCP1901 reduces the number of external discrete components, minimizing board footprint. The resonant controller has an integrated half-bridge driver rated at 600 volts (V), eliminating the need for an external driver or gate drive transformer. A 600 V startup circuit allows direct connection to the bulk capacitor, improving efficiency at light loads through the omission of startup resistors.

Combining both controllers in a single package ensures correct sequencing and operation between the PFC and half-bridge stages. This allows robust power supplies with key protection features, including open feedback loop, and PFC overvoltage and undervoltage protection, to be designed quickly while still maintaining design flexibility.

“The NCP1901 provides a best in class solution for off-line adapters,” said Bill Schromm, senior vice president and general manager of ON Semiconductor’s Computing and Consumer Group. “The integration level achieved translates directly into a smaller form factor. When combined with the higher efficiency of the resonant controller, in either full load or no-load conditions, additional size and cost can be saved through reduction of components and heatsinks.”