The common working modes of PFC(Power-Factor Correction) topology include CCM(Continuous Current Mode), DCM(Discontinuous Current Mode) and CRM(Critical Conduction Mode). PFC topology has a high requirement for MOSFET, and system stability should be improved as much as possible under the condition of ensuring system efficiency and temperature rise. The control loop speed of PFC topology is relatively slow. In order to smooth the AC rectified ripple between 100Hz and 120Hz, the reaction time of PFC topology must reach 10ms. Without special optimization of the control circuit and IC, PFC topology tends to produce a large shock current during the start-up process, which can reach 5-10 times of the normal operation. Especially in the repeated switching process, the MOSFET has a more severe test. MOSFET in PFC topology are bonded between high voltage and ground. The EAS capability of MOSFET is also an important reference to evaluate their reliability during safety testing. Therefore, when choosing MOSFET for PFC circuits, the switching characteristics (Ciss), EAS capability, surge resistance and electrostatic protection capability of MOSFET should be considered in particular.
LLC&PSFB topology is commonly used in high-power resonant converters, which can greatly improve the efficiency of the converter. While significantly reducing switch losses, it can also have higher power density, and can be widely used in server power supply and EV charger, etc. The Z-series GreenMOS is a power MOSFET designed for this type of topology application, with extremely low Qg and a FRD different from conventional SJ MOSFET. While optimizing high-frequency characteristics, that is also a faster reverse recovery speed, which can greatly improve the reliability and efficiency of the system.
The working modes of flyback switching power supply include CCM mode and DCM mode, it is suitable for low power applications such as LED lighting and battery chargers. GreenMOS can provide 600V~900V MOSFETs for flyback topologies and we have also developed the OSS series GreenMOS specifically for quick-charger applications. The OSS series GreenMOS has a lower Qg, faster switching speed, smaller miller plateau, lower Ciss, and optimized nonlinear Coss, which helps developers better solve EMI problems and has competitiveness comparable to GaN MOSFETs.
Our SGTMOS can provide synchronous rectification MOSFET from 30V to 150V. In the selection of synchronous rectification MOSFETs, BV, Rds(on), Qg, and Qrr can be used as references to select suitable MOSFETs. For synchronous rectification applications, we have provided high Vth SGTMOSs that optimizes the consistency of Vth, which makes the device more suitable for parallel use，and it has the advantages of smoother load current and stronger anti short-circuit ability. We also offer smaller package forms such as DFN5*6 with better heat dissipation, which can facilitate circuit board layout and thermal design.
There are two types of forward switching power supplies in hard switching applications: single-transistor forward and two-transistor forward. For the single-transistor forward, when the main switch MOSFET is turned off, the MOSFET will withstand a voltage twice the input voltage. Therefore, in this type of topology application, we recommend high BV MOSFETs to cope with the impact of voltage changes.
The two-transistor forward type is a very stable topology structure with low operation frequency，which is usually applied in conjunction with PFC in 200W~800W adapters, industrial power supplies, computer power supplies, or applications with relatively harsh environments and high stability requirements. In applications, we recommend GreenMOS with smaller thermal resistance and better switching characteristics as the preferred choice.
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