Ultra High Density Offline Power Solutions from ON Semi
Industry’s first Totem pole PFC controller works with silicon, SiC and GaN devices
ON Semiconductor has announced the industry’s first dedicated critical conduction mode (CrM) totem pole PFC controller as a new addition to their solution set for ultra-high density offline power supplies.
The NCP1680 can accommodate any switch type whether it is super junction silicon MOSFET or Wide Bandgap switches such as SiC or GaN devices.In conventional PFC circuits, the rectifier bridge diodes account for around 4 W of losses in a 240 W power supply, representing around 20 percent of total losses. In contrast, PFC stages are typically 97 percent efficient and the LLC circuit achieves similar performance. However, replacing the lossy diodes with switches in a ‘totem pole’ configuration and pulling in the boost PFC function can cut down the bridge losses and significantly improve overall efficiency.
The new NCP1680 CrM totem pole PFC controller employs novel current limit architecture and line phase detection while incorporating proven control algorithms to deliver a cost-effective Totem Pole PFC solution without compromising on performance. At the heart of this IC is an internally compensated digital loop control. The innovative device employs a constant on-time CrM architecture with valley switching. Modern efficiency standards, including those that require high efficiency at light load, can also be met due to inbuilt discontinuous conduction mode (DCM) with valley synchronized turn-on during frequency fold back operation.
This highly integrated device can enable power supply designs for telecom 5G, industrial and high performance computing, that operate with universal mains (90 – 265 Vac) at recommended power levels up to 350 W. With 230 Vac mains input, PFC circuits based upon the NCP1680 are capable of achieving close to 99 percent efficiency at 300 W. Just a few simple components are required externally to realize a fully-featured totem pole PFC, thereby saving space and component cost. Further reducing component count, the cycle-by-cycle current limit is realized without the need for a Hall Effect sensor.
Housed in a SOIC-16 package, the NCP1680 is also available as part of an evaluation platform that allows rapid development and debugging of advanced totem pole PFC designs.
Depending on the switch technology selected for the fast leg of the totem pole, NCP1680 can be used with either NCP51820 half bridge GaN HEMT gate driver or NCP51561 isolated SiC MOSFET gate driver. The NCP51561 is an isolated dual-channel gate driver with 4.5 A source and 9 A sink peak current capability. The new device is suitable for fast switching of silicon power MOSFETs and SiC-based MOSFET devices, offering short and matched propagation delays. Two independent and 5 kVRMS (UL1577 rated) galvanically isolated gate driver channels can be used as two low-side, two high-side switches or a half-bridge driver with programmable dead time. An enable pin will shut down both outputs simultaneously and the NCP51561 offers other important protection functions such as independent under-voltage lockout (UVLO) for both gate drivers and the enable function.
ON Semiconductor offers a wide range of SiC MOSFETs that provide increased efficiency when compared to silicon MOSFETs. The low on resistance (RDS(on)) and compact chip size ensure low capacitance and gate charge (Qg), delivering highest efficiency in a reduced system size, thus increasing power density.
ON Semiconductor has released 650 V SiC MOSFETs in TO-247-4L and D2PAK-7L packages and will continue proliferating this portfolio. In addition, ON Semiconductor has a complete portfolio of silicon based 650 V SUPERFET III MOSFETs.
