D13.13 - High-Density, High-Efficiency GaN-Based 800 V/50 V LLC Converter for Future Datacenters

The rapid progress in artificial intelligence (AI) and machine learning (ML) has driven the development of next-generation, high-performance graphical processing units (GPUs), with multiple devices integrated on a single compute tray to minimize latency. This trend significantly raises the power demand of individual server racks and, consequently, entire datacenters. The conventional 48 V bus architecture is no longer sufficient, as it requires larger copper bus bars and occupies excessive space within the rack for power processing. To overcome these limitations, high-voltage DC (HVDC) bus architectures operating at ±400 V and 800 V have been proposed, which reduce copper volume and improve rack space utilization. Realizing these architectures requires compact, highly efficient 800 V/50 V unregulated DC–DC converters mounted on compute trays. This paper presents the design and implementation of a 6 kW GaN-based LLC converter for this purpose. The prototype achieves a peak efficiency of 98.8% and delivers a power density of 2070 W/in³, demonstrating its suitability for next-generation datacenter power delivery.