The solution achieves an outstanding peak efficiency exceeding 99.2% by integrating ST’s high-performance 650V, 40 mΩ Silicon Carbide (SiC) MOSFETs alongside 600V, 30 mΩ High Voltage MOSFETs housed in TOLL packages. This high efficiency is further enhanced by an optimized gate driving circuit featuring ST’s galvanic isolation gate driver technology (STGAP), which ensures precise switching and minimizes losses. The system is fully digitally controlled by the STM32G474 microcontroller, which supports mixed-signal processing for precise and flexible power management.
Operating in an interleaved configuration, the design significantly reduces ripple current and allows for a smaller output capacitance. Below half load, the system runs in TCM mode, enabling Zero Voltage Switching (ZVS) to enhance efficiency. Above half load, it switches to CCM mode, reducing inductor current ripple and conduction losses. At full load, the power factor remains above 0.98 with total harmonic distortion current (iTHD) below 5%, meeting stringent power quality standards.
This design also utilizes an innovative 2-in-1 inductor, integrating dual inductors into a single magnetic component. This reduces PCB area and component count, enabling a more compact and cost-effective power stage. The improved magnetic coupling lowers core losses and ripple current, reducing stress on output capacitors and enhancing overall system efficiency and reliability. Additionally, the 2-in-1 inductor improves thermal management, supporting stable operation under demanding loads and contributing to longer system lifetime.
Additionally, the design incorporates the STPM32 metering solution on the PFC stage, providing comprehensive power monitoring capabilities. The digital control strategy ensures high efficiency across input voltages from 208 Vac to 277 Vac and load conditions ranging from 10% to 100%. Efficiency remains above 97.88% at 10% load and exceeds 98.46% at full load.
Key features include a wide input voltage range (208-277 Vac), high switching frequency operation (50 kHz to 180 kHz), and robust power factor correction. This reference design represents a highly efficient, flexible, and reliable power solution ideal for demanding server power applications.
