Ericsson's 864W quarter-brick converter addresses high-power datacom demands

Ericsson has announced a second product in its high-power PKM-NH platform, the PKM4817NH-PIHS, which employs the company’s innovative hybrid regulated topology. The platform is optimized for datacom board applications that have a 52–58V system bus distribution and require high-power regulated quarter-brick-format intermediate bus converters.

The new PKM-NH delivers up to 864W with a power density of 35.6W/ cm3 (581W per cubic inch) and follows the PKM4717NH, which was announced earlier this year and offered a high-power handling capability of 750W. To meet the challenge of packing this level of power into a fully regulated quarter-brick format DC/DC converter, Ericsson has deployed its highly 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 between 40V to 60V, which are commonly used in datacom systems.

“Ericsson’s innovative Hybrid Regulated Ratio technology is enabling the delivery of high performance intermediate bus converters that offer the high levels of power increasingly required in the datacom industry,” said Patrick Le Fèvre, Marketing and Communication Director, Ericsson Power Modules. “Offering a power density of more than 35.6W/cm3, the PKM-NH platform is the most advanced fully regulated DC/DC module available for these types of applications.”

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 new PKM4817NH-PIHS module delivers an output voltage from 8.6V to 10.8V at a maximum output current of 80A across an input voltage range of 40V to 60V, within the operational system voltage between 36V and 60V. A product of Ericsson’s ‘design-for-efficiency’ principle, the PKM4817NH has a typical efficiency of 97% at 50% load and offers flat-curve characteristics from 20A to 60A, reducing power losses to the lowest possible level and making a significant contribution to the reduction of energy consumption.

The PKM4817NH-PIHS comes in the industry standard quarter-brick format measuring 57.9 x 36.8 x 14.3mm (2.28 x 1.45 x 0.56-inch). The module comes with two extra power pins to decrease power losses and guarantee optimal current distribution; these two extra power pins were introduced in 2004 and is the most optimized footprint for high-power density DC/DC converters. In addition, the module also comes with a machine-tooled baseplate, guaranteeing excellent thermal conduction and cooling performance.

The PKM4817NH-PIHS provides 2250V input/output (I/O) isolation meeting functional isolation requirements. 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.
Below 50V, in its regulated-ratio mode, the module’s output voltage self-adjusts for optimal operation and secures a regulated 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 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 PKM4817NH-PIHS is also perfectly suitable as a replacement for existing 9.6V intermediate bus applications.
The price of the PKM4817NH-PIHS starts at $74.79 in OEM quantities.

Ericsson