ON Semiconductor, which promotes energy efficiency innovation, recently launched the industry's first dedicated critical conduction mode (CrM) totem pole PFC controller, a new member of the company's ultra-high density offline power solution set.
In the traditional PFC circuit, the loss of rectifier bridge diode in 240 W power supply is about 4 W, accounting for about 20% of the total loss. In contrast, the energy efficiency of the PFC class is usually 97%, and the LLC circuit achieves similar performance. However, replacing the lossy diode with a switch configured with a "totem pole" and pulling in the boost PFC function can reduce the bridge loss and significantly improve the overall energy efficiency. In addition, NCP1680 can be applied to any switch type, whether it is a super junction silicon MOSFET or a wide band gap switch such as silicon carbide (SiC) or gallium nitride (GaN).
The new NCP1680 CrM totem pole PFC controller uses a novel current limiting architecture and line phase detection, combined with proven control algorithms, to provide a cost-effective totem pole PFC scheme without affecting performance. The core of the IC is the internal compensation digital loop control. This innovative device adopts a constant on time CrM architecture with a valley switch. Due to the built-in discontinuous conduction mode (DCM), the valley bottom is conducted synchronously during frequency return operation, so it can meet modern energy efficiency standards, including those that require high energy efficiency under light load.
This highly integrated device allows the power supply to be designed to operate at the recommended power level of up to 350 W on a general-purpose power supply (90 to 265 Vac). The NCP1680 based PFC circuit can achieve nearly 99% energy efficiency at 300 W at 230 Vac power input. Full function totem pole PFC can be realized externally with only a few simple devices, thus saving space and device cost. The number of devices is further reduced to achieve cycle by cycle current limitation without Hall effect sensor.
NCP1680 adopts a small SOIC-16 package, which can also be used as a part of the evaluation platform to support rapid development and debugging of advanced totem pole PFC design.
According to the totem pole switch technology, it includes high-speed half bridge and low-speed half bridge. On the high-speed half bridge, NCP1680 can be used with NCP51820 half bridge GaN high electron mobility transistor (HEMT) gate driver or NCP51561 isolated SiC MOSFET gate driver. NCP51561 is an isolated dual channel gate driver with 4.5 A source current and 9 A sink current peak capacity. The new device is suitable for fast switching of silicon power MOSFET and SiC based MOSFET devices, providing short and matched propagation delay. Two independent 5 kVRMS (UL1577 class) electrically isolated gate driver channels can be used as two lower bridge, two upper bridge switches or one half bridge driver, with programmable dead time. One enable pin will turn off both outputs at the same time, and NCP51561 provides other important protection functions, such as independent undervoltage locking (UVLO) and enable function for two gate drivers.
Sammy Semiconductor provides a wide range of SiC MOSFETs, which provide higher energy efficiency than silicon MOSFETs. Low on resistance (RDS (on)) and compact chip size ensure low capacitance and gate charge (Qg) to provide the highest energy efficiency in a smaller system size, thereby improving power density. The 650V SiC MOSFET packaged with TO-247-4L and D2PAK-7L has been released by Ansenmey Semiconductor, and will continue to expand this product line. In addition, Ansenmey Semiconductor provides a complete 650 V SUPERFET on silicon ® III MOSFET product portfolio.
