E0177 - PKM-NH

June 2013
Ericsson Regulated Quarter-Brick
Module Raises the Bar to 750W for
High-Power Datacom Applications
Industry’s first 750W Hybrid Regulated Ratio DC/DC converter
Quarter-brick module delivers high power density of 31.12W/cm3 per cm3 (508W per
cubic inch)
Highly-innovative regulated-ratio topology module delivers high-efficiency flat-curve
characteristics of up to 97%
Ericsson has unveiled an industry first with its new hybrid-regulated topology. The new PKMNH platform is optimized for datacom board applications that have a 52V/54V system bus
distribution and require regulated high-power quarter-brick-format intermediate bus converters
able to deliver up to 750W.
To meet the challenge of packing a 750W regulated DC/DC converter in a quarter-brick
format, Ericsson has developed an innovative proprietary topology known as Hybrid
Regulated Ratio (HRR). The topology combines two power-control methods – voltageregulation and ratio-regulation – resulting in high performance across the input voltage ranges
used in datacom systems, which are usually between 40V to 60V.
The HRR topology implemented in the Ericsson PKM-NH platform delivers an excellent
response to line or load transients and guarantees the output voltage will remain stable and
immune from voltage deviation due to power disturbances on the system bus voltage. This
means it retains intermediate bus voltage integrity within the tolerance band required by power
system architects.
The PKM4717NH is the first product in the PKM-NH series. The module operates with an
input voltage range of 40V to 60V and delivers an output voltage of 10.8V at 70A within the
operational system voltage between 50V and 60V. Below 50V, in its regulated-ratio mode, the
output voltage self adjusts for optimal operation and secures a stable voltage even though the
system bus voltage could be operating in abnormal mode. Retaining a stable and regulated
voltage while the system bus runs its normal operational voltage becomes a highly important
capability to avoid traffic disruption and also to provide enough time for system monitors to
take required action, either to turn on redundant power units or potentially to shut down part of
the system.
June 2013
Based on a bus-voltage optimization study carried out by Ericsson, the optimal fixed voltage to
limit board conduction losses during step-down conversion at the Point-of-Load (POL) is
believed to be 10.8V in non-‘dynamic-bus-voltage’ applications. This bus voltage is very
common in datacom applications that no longer require the standard 12V supply to power disk
drives. However, if this level is required for local sub-functions, then step-up POL converters
can easily generate a 12V supply. The PKM4717NH is also perfectly suitable as a
replacement for existing 9.6V intermediate bus applications.
“The increased demand for high-power DC/DC converters in the datacom industry is pushing
power density to unprecedented levels, requiring designers to explore new possibilities in
power conversion technology,” said Patrick Le Fèvre, Marketing and Communication Director,
Ericsson Power Modules. “The PKM4717NH is a breakthrough product and is the first based
on the truly innovative Hybrid Regulated Ratio technology developed by Ericsson. Offering a
power density of 31.12W/cm3 (508W/in3), the PKM4717NH is the most advanced regulated
DC/DC power module for datacom applications.”
A product of Ericsson’s ‘design-for-efficiency’ principle, the PKM4717NH has a typical
efficiency of 97.1% at 60% load and offers flat-curve characteristics from 20A to 70A, reducing
power losses to the lowest possible level and making a significant contribution to the reduction
of energy consumption.
The PKM-NH series implements the high-power industry-standard footprint with two extra
power pins to decrease power losses and guarantee optimal current distribution. The two
extra power pins were introduced in 2004 and is the most optimized footprint for high-power
density DC/DC converters. However, Ericsson also offers an optional version, with the ‘SP’
reference, which is compatible with traditional five-pin intermediate bus converters.
The PKM4717NH provides 2250V input/output (I/O) isolation meeting functional isolation
requirement. It includes a number of I/O protection and operational features including input
overvoltage suppression, soft-start for handling of high capacitance loads, delayed hiccup
over-current protection, over-temperature protection, over-voltage and under-voltage lockout,
and pre-bias startup functionality.
The PKM4717NH comes in the industry standard quarter-brick format measuring 59.9 x 36.8 x
11.4mm (2.28 x 1.45 x 0.45-inch). The PKM-NH series is also available with a baseplate for
applications requiring additional cooling or a cold-wall attachment.
June 2013
Patrick Le Fèvre, Marketing and Communication Director, Ericsson Power Modules
+46-10-716 95 07
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