Infineon Technologies AG has introduced a 24 kW battery backup unit (BBU) DC-DC reference design for high-voltage (HV) DC bus architectures in artificial intelligence (AI) data centers. The solution is the first reference design of its kind to operate directly from a battery stack to an 800 V DC bus using both 650 V and 1200 V silicon carbide (SiC) technologies. It delivers a power density of 450 W/in³ and efficiency exceeding 99%, while maintaining the same physical form factor as current low-voltage BBU implementations.

The reference design addresses a key infrastructure challenge as data centers increasingly transition toward higher-voltage DC power distribution architectures.

“Powering AI at scale demands a systemic approach that optimizes every stage of the power delivery chain, from grid connection to the processor core,” said Magdalene Boebel, Senior Vice President and Business Line Head Power System ICs at Infineon. “Our 24 kW high-voltage BBU reference design, operating directly on an 800 V DC bus, sets a new benchmark in power density and efficiency, giving data center architects a fully integrated solution to meet the most demanding AI infrastructure requirements.”

The design is based on a multi-level, multiphase non-isolated architecture that combines stacked, interleaved, and coupled boost and buck stages. This architecture reduces magnetic component volume without relying on flying capacitors. A shared switching-leg topology creates a common current path between charge and discharge stages, enabling zero-voltage switching (ZVS) across the operating range.

According to Infineon, this approach reduces current ripple, supports fully integrated magnetics, and delivers fast transient response capabilities that are increasingly important as AI server power consumption becomes more dynamic and less predictable.

The compact module measures 112 mm × 88 mm × 118 mm and integrates a 24 kW main power stage together with a 2.4 kW auxiliary power supply. Charger and discharger sections share key components, including the EMI filter, capacitors, and protection MOSFETs, helping to reduce the overall component count. The design also incorporates silicon carbide junction gate field-effect transistors (JFETs) for ORing and hot-swap functionality, while a planar transformer combined with CoolSET™ technology implements the auxiliary switched-mode power supply in a compact footprint.

At the core of the DC-DC conversion stage is the CoolSiC™ MOSFET IMT65R033M2H, a 650 V device qualified for bidirectional buck-boost DC-DC operation in high-voltage BBU applications. The device’s low conduction and switching losses support conversion-stage efficiencies above 99%, reducing thermal load at rack level.

During grid disturbances, generator transitions, or power outages, the device enables rapid energy transfer between the HV DC bus and the battery with minimal losses. The IMT65R033M2H features a 650 V breakdown voltage rating, robust body diode, 175°C junction temperature capability, and Infineon’s .XT packaging technology to support operation under voltage spikes, high dv/dt transients, and continuous thermal cycling. Consistent gate-threshold voltage characteristics across devices also simplify multi-phase system design and support redundant rack configurations.

The architecture is documented in Infineon’s REF_12KW_HFHD_PSU reference design, which demonstrates the use of the IMT65R033M2H in high-power DC-DC stages for rack-level HV BBU applications.

The complete bill of materials includes CoolSiC 650 V Generation 2 MOSFETs, including the IMT65R033M2H, EiceDRIVER™ gate drivers, TLE497x current sensors, PSOC™ Performance line microcontrollers, CoolSET™ ICs for the auxiliary power supply, and a 1.7 kV SiC MOSFET.

Additional design features include reduced common-mode noise with negligible AC components and fully integrated magnetics. The design utilizes three power cards that provide mechanical connections for the positive DC, negative DC, and midpoint rails, while also serving as structural elements within the assembly, contributing to the solution’s compact footprint.

As data center operators move toward higher-voltage DC bus architectures to improve efficiency and reduce power distribution losses, battery backup units are becoming increasingly important for maintaining uninterrupted power delivery to AI servers during grid events. Infineon stated that the 24 kW HV BBU reference design demonstrates how silicon carbide-based DC-DC conversion can address the power density, efficiency, and reliability requirements of next-generation AI infrastructure.

The company’s broader power portfolio spans silicon (Si), silicon carbide (SiC), and gallium nitride (GaN) technologies, covering power conversion requirements across the entire power delivery chain from the electrical grid to the processor core.

Original – Infineon Technologies