How to reduce the loss of the last inch in the data center? Infineon presents a comprehensive solution

Today, the rapid development of generative artificial intelligence (AI) has brought about an explosive growth in data processing needs. There are currently about 8,500 data centers in the world, and 150 more are planned to be built this year to cope with the growing demand for data storage and processing. These data centers not only vary in size, but also become more efficient and powerful with the advancement of technology. In particular, hyperscale data centers can accommodate tens of thousands of racks and support huge workloads and processing capabilities.

Data Center Power Challenges

The power demand of data centers has risen sharply as the number of AI processors has increased. Typically, there are about 50 CPUs and 24 AI processors in a rack. A data center with 10,000 racks may contain 240,000 AI processors and 500,000 CPUs. These processors not only require a lot of electricity to run, but also require efficient cooling systems to prevent overheating. Currently, the power of a rack is about 16 kilowatts, and the power of the next generation of racks is expected to reach 125 kilowatts. Such power demand poses a severe challenge to the power conversion and distribution system of the data center.

Currently, the single-chip power consumption of high-end GPUs is as high as 1 kW, and will reach 2 kW or more by the end of the 2020s, which will increase the total energy demand of data centers. According to the International Energy Agency (IEA), data center power consumption will account for about 2% of the world's total power consumption in 2022, and by 2030, data center power consumption will account for 7% of the world's total power consumption, equivalent to India's current power consumption.

The importance of conversion efficiency

Power conversion efficiency is critical to the operation of data centers. There are multiple links in the current conversion of data centers, including stepping down the high-voltage AC to the rack, converting the AC voltage to 48V DC, and finally powering the 0.7V processor after different step-down stages. Each link requires efficient power conversion. This includes digital controllers and power stages, which work together to ensure that the processor gets the required voltage and current.

At present, the efficiency achieved by AC/DC power supplies has exceeded 97%, and the intermediate DC-DC conversion efficiency has reached 98%, but the efficiency at the load point is usually around 90%, which is currently the most critical part for improving the overall conversion efficiency.

For this reason, the industry is currently adopting technologies such as 48V bus and vertical power supply to reduce the last inch PDN (power delivery network) loss and maximize system efficiency.

Infineon's response

In June 2024, Infineon released a product roadmap for power supply units (PSUs) for AI system energy supply. In addition to the already launched PSUs with output power of 3 kW and 3.3 kW, the new 8 kW and 12 kW PSUs will also further improve the energy efficiency of AI data centers in the near future. With the 12 kW reference board, Infineon is about to launch the world's first power supply unit that reaches this performance level to power future data centers.

Infineon is also responding to data center operators’ demands for higher system efficiency and less downtime. The rise in server and data center applications has increased the demand for power supplies, resulting in the need to develop power supplies with power ratings from 800 W to 5.5 kW and even higher.

At this year's PCIM 2024 exhibition, Infineon also showcased a number of power management solutions designed specifically for data center applications to demonstrate the company's layout and determination in this field.

Infineon Technologies offers a range of solutions including Silicon Carbide (SiC), Gallium Nitride (GaN) and Silicon Power Devices. These semiconductor technologies offer higher efficiency and power density while reducing system cost and complexity.

The different product combinations are the perfect match to solve AC/DC power supply challenges. For example, in AC-DC power supplies, a totem pole topology can be used, using silicon carbide in the fast switching arm and super junction silicon in the slow arm.

In addition, GaN can be used in 400V-48V DC/DC converters to convert 400 V DC to 48 V DC. GaN can also be used for synchronous rectification on the 48 V bus.

This year, Infineon has expanded the production scale of silicon carbide and gallium nitride to meet the strong market demand. In August, Infineon announced that the first phase of its new wafer fab in Malaysia has officially started operation. After completion, the plant will become the world's largest and most competitive 200 mm silicon carbide power semiconductor wafer fab. In September, Infineon once again announced the successful development of the world's first 300 mm gallium nitride power semiconductor wafer technology, becoming the world's first company to master this breakthrough technology in an existing and scalable large-scale production environment.

At the exhibition, Infineon developed a 3.3kW PSU dedicated Demo board for the AI ​​server 54V output platform. It uses Infineon's CoolGaN, CoolSiC, CoolMOS designs, as well as Infineon's own control chip XMC series and other complete solutions. It can achieve a benchmark efficiency of 97.5% for the whole machine and a power density of up to 96W per cubic inch, solving the high power requirements of data center PSUs.

Vertical Power Supply: Optimizing Power Flow in AI Servers

In order to shorten the distance between the point-of-load stage and the actual processor, Infineon's vertical power delivery solution minimizes the losses in the PDN by placing the power module directly below the processor. This design not only improves efficiency but also allows for a more compact system design.

For example, the OptiMOS dual-phase power module on display integrates two OptiMOS 6 power stages with inductors and capacitors on a single substrate. This level of integration allows the two phases of a multi-phase buck regulator to be deployed in a 40% smaller area compared to an equivalent discrete solution. Infineon's dual-phase module uses a proprietary top inductor design that improves thermal and electrical performance, resulting in superior energy efficiency.

The TDM22544D & TDM22545D dual-phase power module solutions have the industry's best power density: 10x9x8 mm and 10x9x5 mm, with a peak current of 160 A. Vertical power supply can be achieved, and the efficiency is 2% higher than similar products at full load, and the temperature is 5°C lower than similar products.

48 Volt Intermediate Bus Converter

Compared with the 12V power supply architecture, the 48V system reduces the current under the same power conditions by increasing the bus voltage. According to P=IR, the conduction loss in the PDN is reduced, thereby improving product efficiency.

In the 48 V power supply architecture, Infineon introduces new intermediate bus converter (IBC) solutions, the so-called hybrid switched capacitor (HSC) and zero voltage switched capacitor (ZSC), to achieve high efficiency and high power density applications. Infineon's 48V architecture is designed for mass production of hyperscale data centers and AI servers. The architecture optimizes discrete MOSFETs, driver ICs and controller ICs, enabling design innovations throughout the entire power conversion chain.

The ZSC topology is a 12 V unregulated rail provided by a 48 V bus voltage. This topology mainly relies on switches and capacitors to transfer power from a high voltage rail to a low voltage rail and is fundamental to achieving zero voltage switching operation, thereby increasing switching frequency and power density.

Following the trend of miniaturization of package size, proximity to digital loads and high switching frequencies, systems require low voltage inputs at multiphase step-down levels. To achieve higher conversion ratios, Infineon introduces hybrid switched capacitor (HSC) converters, which combine the advantages of switched capacitor converters with the high step-down ratio capability of magnetic devices. By transferring power through capacitors and magnetic devices, the converter can significantly improve efficiency and power density. However, the 12 V bus rail also requires high power density close to digital loads. For such applications, a 2:1 ZSC solution can be used, which has very high power density and efficiency, and has outstanding results.

Don't underestimate a small step

As AI grows exponentially, so too does the energy consumption of chips supporting data growth, making power solutions and architectural innovations critical to having a measurable impact on global energy savings and better total cost of ownership (TCO) for data centers.

Although power efficiency improvements may seem like only 1 or 2%, this efficiency improvement at the board level can multiply exponentially for data centers with large system sizes.

According to Infineon, for a typical data center with approximately 100,000 processors, a small improvement in efficiency could save more than 7 megawatts of electricity, equivalent to $14 million in annual electricity savings.