Ericsson has unveiled what it claims is an industry first with its new hybrid-regulated topology. The new PKM-NH platform has been optimised 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.
In order to pack a 750W regulated DC/DC converter into a quarter-brick format, Ericsson has developed an innovative proprietary topology known as Hybrid Regulated Ratio (HRR). The topology combines two power-control methods – voltage-regulation 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 has been able to deliver 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 and 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.
Based on a bus-voltage optimisation 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 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. “We believe 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.