As AI servers demand more power, rack architectures are shifting to higher voltages. A reference design demonstrates direct conversion from 800V DC to 6V.
Navitas Semiconductor and Microchip Technology have developed an 800V DC-to-6V DC reference design for AI data centre racks based on the Open Compute Project’s (OCP) 800V DC architecture.
The design takes a different approach to rack power conversion by stepping 800V DC directly down to 6V DC. Instead of using separate 800V-to-50V and 50V-to-6V stages, the two conversions are combined into a single converter. This can reduce the number of conversion stages between the rack’s high-voltage supply and the power required by GPUs and server boards.
The power stage uses 16 650V gallium nitride (GaN) FETs arranged in a stacked half-bridge topology. The devices can switch at up to 1MHz, while the reference design targets 96% peak efficiency at full load and a power density of 2,100W/in³. A dual-side-cooled package is used to manage thermal performance within the compact power stage.
The compact architecture is also intended to bring the power conversion closer to the GPU board. Its low-profile design can support close integration with the load, an important consideration as AI racks pack higher power levels into increasingly constrained spaces.
Microchip’s dsPIC33AK digital signal controllers handle the power-conversion control. The 200MHz 32-bit controllers combine high-resolution pulse-width modulation with multiple 12-bit analogue-to-digital converters capable of operating at up to 40MSPS. These capabilities support the fast control loops needed for high-frequency DC/DC conversion.
The reference design also incorporates hardware-based security alongside power control. Its security device supports secure boot, code authentication, trusted firmware updates, key management, and root-of-trust functions.
The platform is supported by reference hardware, software, and design documentation, giving engineers a way to evaluate the 800V-to-6V architecture for high-power AI data centre applications.
