Page 7 - PEN eBook May 2025

COVER STORY—DESIGN

systems that necessitate the consumption of yet throughout each data center. Processor requirements
more power. are commonly about 1 V .
DC
Meeting the data center industry’s projected Optimizing each stage of this process is vital to
demand for electricity will require enormous global minimizing energy loss and maximizing efficiency.
investment to build many new power plants. This This is where high-performance MOSFETs are crucial.
explains the heightened imperative to also make data
centers as energy-efficient as possible. THE ROLE OF MOSFETs
MOSFETs are integral to efficient power conversion,
DATA CENTER POWER EVOLUTION starting with bringing in 208- to 277-V input and
AC
One of the most important measures the industry in each step down through 48 V, 12 V, 6 V, and 1 V or
has adopted to make data centers more energy- less, moving through the power delivery network from
efficient is transitioning from an intermediate bus racks to boards to ICs. MOSFETs are also required for
voltage of 12 V to a 48-V power delivery architecture. conversions of AC to DC along those paths.

A rack typically holds four or more servers. Any MOSFETs are integral to power delivery systems and
given rack that consists of servers running CPUs in several rack and server subsystems. These include
might use 3 kW to 5 kW today, but a rack filled switched-mode power supplies (SMPSes), power
with servers running high-performance GPUs and supply units (PSUs), intermediate bus converters
accelerators processing AI workloads uses 10 kW to (IBCs), points of load (POLs), and battery backup units
100 kW or even more. (BBUs).

The consequences are easily predicted. Assuming A given in power design is to use MOSFETs that
a consistent voltage, resistance goes up as the exceed the stated voltage, so the adoption of a
current increases (P = I R), translating into mounting 48-V interim bus dictates the use of 25-V to 650-V
2
transmission losses. Not coincidentally, currents in MOSFETs.
data centers are expected to keep increasing at a
steep rate. Power from the grid entering a data center passes
through an SMPS, typically a Titanium-class SMPS
Given all that, moving to a higher voltage was (by definition, having efficiencies greater than 97%).
necessary to minimize transmission losses and Data centers commonly specify Titanium-class power
enable a more efficient way to transfer power. The technology, which is to say, the most energy-efficient
move to a 48-V architecture in data centers was versions available.
initiated several years ago.
PSUs
As the AC power from the data center enters the The average power supply shelf in a rack
rack, it is converted to DC and stepped down in incorporates a half-dozen PSUs. MOSFETs are used
voltage several times, increasingly to 48 V, then to in PSUs for power-factor correction (PFC), in the
12 V or 6 V, and finally to the precise voltages that isolated DC/DC power converter on both the primary
meet the various needs of the range of processors and secondary sides, and MOSFETs can be used
(CPUs, GPUs, TPUs) used in different servers installed instead of diodes in ORing circuits at the DC output.

MOSFETs are critical elements in multiple subsystems in data center power delivery networks, helping to step down voltage
and condition the power. These subsystems include SMPSes, PSUs, IBCs, POLs, and BBUs.

MAY 2025 | www.powerelectronicsnews.com 7