864W quarter-brick DC/DC module for datacom supplies
The second product in the high-power PKM-NH format, the PKM4817NH-PIHS is optimised for datacom board applications that have a 52–58V system bus distribution and require high-power regulated quarter-brick-format intermediate bus converters.
The PKM-NH follows the PKM4717NH, which has 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 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.
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. 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. It 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-in.). 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 the package claims to be the most optimised 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.
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 disc 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 suitable as a replacement for existing 9.6V intermediate bus applications.
Ericsson Power Modules; www.ericsson.com/powermodules
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