DC/DC converters meet the challenges of hyperscale data centers
Introduction
Driven by insatiable demand for cloud-based storage and processing, data centers are expanding at an unprecedented rate. The total worldwide capacity of today’s hyperscale data centers, the largest types, has doubled in the last four years, and continues to grow[1].
This expanding data center capacity feeds an ever-increasing demand for more power. Components need to be reliably supplied with energy, and efficiency remains a top priority. At the same time, there’s an increasing need for compact systems with higher power density that can work with liquid cooling systems with reduced heat dissipation to reduce the cost of thermal management.
The shift to 48V
In response, one of today’s trends is a shift away from 12V as the standard to distribute DC power within the data center, and to instead use 48V. Increasing the voltage fourfold reduces the required current by the same factor. This means that conduction losses are reduced by a factor of 16 (as they are proportional to the square of the current), thus improving efficiency and reducing the heat dissipated, while busbars can be smaller.
At the same time, data centers are still full of systems and components that need a well-regulated 12V supply, where the output voltage of the power supply doesn’t fluctuate with variations in input voltage. Examples of components needing regulated 12V supplies include PCIe cards, certain memory types, disk drives or SSDs for storage, and cooling fans.
In practice, the input voltage can often vary in a data center, and not all power system topologies are able to cope with this. This is reflected in chamber tests by the Open Compute Project (OCP), where varying and noisy input voltage is introduced.
Hyperscale data centers need modular, scalable power systems that can be deployed quickly if needed – for example, if a customer moves equipment around in their racks, or adds new computing or storage capacity.
Efficient module for high power density
For power system designers, this means they need to find a solution that takes a 48V input and can deliver a regulated 12V output. The solution needs to have high efficiency and be small enough to fit in today’s cramped data center racks.
To meet these demands, Flex Power Modules has developed the quarter brick BMR35x series of digital power modules. This is the company’s ninth generation of digital quarter bricks, and this extensive experience has enabled it to deliver an efficient, optimized device for data center applications. The modules employ an innovative transformer-coupled non-isolated topology which reduces component count and current stresses.
The BMR35x series is also well suited for multiple telecom applications, which have demanding requirements for the suppression of transients in the input voltage. BMR35x handles noisy environments and input voltages with ease, whether in telecom as well as data centers.
There are three devices in the series, with different power ratings: the BMR350 can deliver 1300W (continuous) output power and 1700W (peak) for a limited time, while the BMR351 can provide up to 1600W (continuous) and 2320W (peak). Finally, the BMR352 delivers up to 2000W (continuous) and 3000W (peak).
Supporting peak power capabilities is particularly important for load transients or scenarios where compute demand spikes. For example, supporting a processor’s turbo mode or system boot-up may require a momentary surge well above steady-state ratings. These modules are engineered to absorb those peaks reliably, often with the ability to retain operational data and manage recovery effectively in the event of a controlled shutdown.
Active Current Sharing (ACS) allows the modules to be paralleled for higher total output and greater flexibility in scalable power system design if required. Dynamic Load Sharing (DLS) enables stable load distribution across modules, preventing thermal hotspots and improving overall system reliability.
Efficiency is high across the range, with the BMR352 achieving up to 97.9% at half load. Each module has an input voltage range of 40V to 60V.
The modules include a PMBus® interface for digital configuration, monitoring and control, and are supported by the Flex Power Designer tool. They also include an Event Data Recorder which automatically stores essential information in non-volatile memory in case of a fault, shutdown or catastrophic failure, to help with fault diagnosis and failure analysis.
To improve thermal management, the three power modules have been designed with thermal conduction paths from heat-dissipating components moved to the top baseplate to enable direct heat removal. BMR35x offers great opportunities for advanced cooling solutions that, together with its class-leading efficiency, enable it to provide a very high-power output for its form factor.
Conclusions
To meet our relentless demand for cloud storage and computing power, data centers continue to scale in size with faster processors and higher-specification components demanding ever more power. They require highly efficient power supplies capable of converting 48V to 12V while minimizing heat dissipation and maximizing power density.
To meet the relentless demand for reliable power solutions in data centers, Flex Power Modules has developed the BMR35x range of DC/DC converters which provide excellent efficiency and the industry’s highest peak power capability in a quarter brick module. Together, these solutions underline how the company is supporting smarter, futureproof power delivery from grid to chip.