High-Power Totem Pole PFC Controller Meets Challenging Efficiency Standard

onsemi introduced its latest mixed-signal controller dedicated to bridgeless totem pole PFC (TP PFC) topology. The NCP1681 targets ultra-high density offline power supplies. Building upon the success of the NCP1680, which is suited for designs up to 350 W, the new controller extends the power capability into the kilowatt range.

In the past, TP PFC designs required the use of an MCU that added design complexity and the need for coding. However, with the NCP1681, only a few external components and no coding is needed to be added for a fully-featured TP PFC solution, thereby saving time, cost and space. 

The NCP1681 can be configured to work in either fixed frequency continuous conduction mode (CCM) or multi-mode operation, where the controller naturally transitions between CCM and critical conduction mode (CrM) for optimal performance across power levels. 

The new NCP1681 high power TP PFC controller integrates established control algorithms with novel features to deliver a high performance and cost-effective TP PFC solution. Challenging efficiency standards such as ‘80Plus’ or ‘CoC Tier 2’, that require high efficiency over a wide load range, can also be met.

The new NCP1681 is suited to higher-power power supplies from 350 W to several kilowatts range that operate on universal mains input (90 – 265 Vac), addressing a wide range of applications including server, high performance computing, telecom, industrial and OLED TV. At high line, NCP1681 TP PFC solutions will achieve close to 99% efficiency. 

Alongside the TP PFC controllers, onsemi offers a wide range of  MOSFETs and  isolated gate drivers that can be used for the fast leg of the totem pole. SiC MOSFET devices have low on resistance (RDS(on)) and compact chip size which ensures low capacitance and gate charge (Qg), delivering highest efficiency in a reduced system size, thereby enabling power density. When NCP1681 is used with  NCP51561 galvanically isolated gate driver, robust design can be realized without sacrificing switching performance.  

Learn more here.