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Figure 1. Connected devices are expected to produce 500 zettabytes of data annually by 2020.
48Vdc input and 12V output voltages
were historically chosen to minimize
down-conversion losses and losses
proportional to current and distance
when supplying typical server boards.
However, given the changes in core
voltage, current draw, maximum
power and the difference between full-
load and no-load power, these fixed
voltages are less suited to maintaining
optimal efficiency in modern systems.
The ability to set different voltages,
and change these dynamically in real-
time, is needed to allow a system to
adapt continuously for best efficiency.
Adaptive Control
Requires a Common
Protocol
PMBus is an industry-standard protocol
for communicating with digitally
controllable power supplies from the
front-end, through the advanced bus
and to the point-of-load converters
(figure 2). By monitoring the status of
Alleviating the Energy
Consumption Concern
While
looking
at
potentially
establishing
higher
maximum
equipment operating temperatures to
save on cooling costs, operators also
recognize the importance of improving
the overall energy efficiency of data
center equipment; to reduce the
direct energy consumed but also the
heat generated and hence the cost of
cooling.
Maximizing efficiency at every point
is vital, throughout the servers,
their power supplies and through
the system-management software.
Despite this, peak power consumption
continues to increase to meet the
demands for increased computing
capability and the consumption of a
typical server board has increased
from a few hundred watts to 2kW or
3kW today, and could reach 5kW or
more in the future. As a result, there
is a growing difference between the
server’s minimum power at light load
and its power at full-load. Fortunately
power distribution architectures are
becoming more flexible, with real-time
adaptive capabilities that maintain
optimal efficiency under all operating
conditions.
Adapting the Power
Architecture
A distributed power architecture
typically comprises an Intermediate
Bus Converter (IBC) that operates
from a 48Vdc input supplied by a
front-end AC/DC converter, as shown
in figure 1. The IBC provides a 12V
intermediate bus that supplies low-
voltage DC-DC point-of-load (POL)
converters positioned close to major
power-consuming components on the
board, such as processors, System
on Chips or FPGAs. Multiple POLs
may be used to supply core, I/O and
any other voltage rails. The IBC’s
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