With the availability of fast switching wideband gap transistor SiC and GaN based power switches, which have minimal reverse recovery charge along with other advantages, Totem Pole PFC designs can now operate in CCM mode to provide higher efficiency and higher power. In addition, the peak current will be 2 times of a CCM PFC, which increases the difficulty of EMI filter design and efficiency optimization. When using a BCM PFC, the operation frequency varies widely. But both have challenges.Ī DCM PFC can only support low power applications. This means that the Totem Pole PFC can only work in DCM (Discontinuous Conduction Mode) or BCM (Boundary Conduction Mode) mode with traditional Si-MOSFET. (A DCDC boost converter provides output voltage higher than the input voltage.) For a synchronous-rectified boost, a big problem is reverse recovery charge of the MOSFET body-Diode if the converter works in CCM (Continuous Conduction Mode) condition. Why SiC-MOSFET is needed in Totem Pole PFC designĪs Figure 2 shows, Totem Pole PFC can be considered a synchronous-rectified boost DCDC converter.
#HIH CURENT TOTEM POLE OUTPUT PLUS#
The Energy-Star 80 PLUS efficiency specification (introduced in 2007) adds higher efficiency levels for AC/DC rectifiers from Gold to Platinum and on to the Titanium level.įigure 1: a) Bridgeless PFC, b) Totem Pole PF Design Consideration of Totem Pole PFC Higher efficiency and size are always an important concern in the design of a switching mode power supply, especially for energy saving and environmental protection. The fast switching wideband gap Silicon Carbide (SiC) or Gallium Nitride (GaN) power switches and isolated single chip current sensors in bridgeless Power Factor Correction (PFC) and DCDC converters helps to improves efficiency and thermal management, and to reduce both size and component count to simplify PCB circuits.
To meet the power efficiency and size improvement goals, design of systems need to exploit the advancement in power switches and utilize better suited architectures and solutions in the circuit. One such example is power supplies that are pushing to meet 80 Plus Titanium efficiency levels for wide variety of power conversion applications such as telecom, server and data center or other industrial power supplies. These trends put lots of pressure on power engineers and architects to extend existing power technology boundaries to achieve higher system efficiencies, faster response times, and reliable and robust, smaller size solutions with reduced part counts for lower cost in new generations of electronics system designs. The overall global electrical power demand is also rapidly increasing and is also driving additional demand. Worldwide, the Electronics Industry is seeing substantial changes – driven by Artificial Intelligence, cloud based IoT, next generation RF technologies, Electric Vehicles (EV) and their Advance Driver-Assistance Systems (ADAS) and Autonomous Driving needs, – to the widespread adoption of wide-bandgap power switches based on Silicon Carbide (SiC) and/or Gallium Nitride (GaN) semiconductors.
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