EPC Unveils Revolutionary 5 kW GaN AC-DC Reference Design for Data Centers
EPC has unveiled a groundbreaking reference design, a 5 kW AC-to-48 V DC conversion system, leveraging enhancement-mode gallium nitride (eGaN) power devices. This innovative solution addresses the escalating demands of AI server racks and high-power data center infrastructure. With a focus on efficiency and density, the design employs a front-end four-level totem-pole PFC stage and an isolation stage of modular LLC converters, achieving an impressive 96.5% system efficiency and a power density of 116 W/in³.
The design’s significance lies in its ability to tackle the challenges posed by the growth of AI and cloud computing. As these technologies demand more power, traditional power conversion systems face limitations in size, thermal management, efficiency, and cost. EPC’s reference design leverages GaN’s high-frequency switching, low on-resistance, and compact electromagnetic components to overcome these bottlenecks.
The 5 kW, 4-level totem-pole PFC evaluation board is a key component. It utilizes the EPC91107KIT module, featuring a 4-level flying-capacitor totem-pole PFC topology with EPC2304 GaN FETs. This design significantly reduces inductor requirements, resulting in a 9x smaller PFC inductor and a 40% smaller EMI filter compared to conventional two-level designs. It operates at a switching frequency of ~140 kHz with a nominal input of 240 V AC and ~25 A input current, achieving a peak efficiency of ~98.5% at 5 kW.
On the isolation side, EPC employs the EPC91110KIT, which uses four modular 1.375 kW LLC converters in an Input-Series Output-Parallel arrangement. Each module, powered by EPC2305 GaN FETs, achieves 98.2% peak efficiency, delivering a combined ~5.5 kW output. The overall system efficiency is ~96.5% for the full AC-to-48 V chain, with a compact footprint power density of 116 W/in³.
The high switching frequency and reduced passive component size enabled by GaN contribute to this density uplift, allowing for smaller inductors, EMI filters, and improved thermal management. This design is particularly crucial in the AI age, where server power requirements are soaring. As AI workloads demand more power, power conversion systems’ efficiency and density become critical design constraints in data center infrastructure.
The rising adoption of 48 V distribution rails is a response to these challenges, reducing I2R losses and enhancing overall rack efficiency. EPC’s 5 kW reference design directly addresses these evolving demands, offering a high-efficiency, compact, and scalable blueprint for next-generation compute environments. With a system efficiency of 96.5%, the design minimizes conversion losses, reduces thermal dissipation, and improves overall system reliability, making it ideal for AI applications.
The design’s power density of 116 W/in³ enables a compact power shelf footprint, allowing for higher server density within standard ORv3 racks. Engineers can increase compute density or simplify cooling infrastructure without sacrificing valuable rack space. The four-module ISOP configuration of the isolation stage enhances scalability, enabling designers to extend the system from 5 kW to 33 kW, 48 kW, or even 108 kW with minimal architectural changes.
Furthermore, the AC-to-48 V topology aligns with industry trends. Many data centers are transitioning from traditional 12 V rails to higher voltage distribution, particularly 48 V or higher, to reduce transmission losses in long cable runs and dense rack environments. EPC’s solution, integrating GaN-based four-level totem-pole PFC with a modular LLC architecture, provides an electrically congruent solution, aligning with the industry’s direction.