750W from regulated quarter-brick module for high-power datacom applications

June 13, 2013 // By Graham Prophet
A quarter-brick module delivers high power density of 31.12 W/cm3 (508W per cubic inch); its innovative regulated-ratio topology module delivers high-efficiency flat-curve characteristics of up to 97%.

Ericsson claims an industry first with its new hybrid-regulated topology. The PKM-NH platform is 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.

To meet the challenge of packing a 750W regulated DC/DC converter in a quarter-brick format, Ericsson has developed a 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 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.

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