Advanced Bus Converter powers Network-Attached-Storage applications with high capacitive loads

February 11, 2013 // By Paul Buckley
Ericsson has launched what the company claims is the industry's first digitally controlled Advanced Bus Converter aimed at powering Redundant Array of Independent Disks and Network Attached Storage hard-disk applications that operate with high capacitive loads up to 15 mF.

Based on the Ericsson 3E FRIDA II platform the BMR456 'High-Cap' series (BMR4560004/018) guarantees stable and accurate 12 V bus voltage over the full input-voltage range.     

RAID and NAS applications developed for datacenters are designed for high performance and reliability and require very stable and smooth bus voltages without disturbances, such as voltage glitches or delays that result from power sources operating with current-mode limitations. Designers will commonly use large arrays of capacitors, often resulting in an average value of 12 to 15 mF, to secure that the bus voltages delivered to hard disks and other sub-assemblies are exempt from noise.     

Developing these types of products can be a challenge, but the BMR456 'High-Cap' converter makes full use of the flexibility offered by digital control in addition to its Ericsson Energy and Performance Optimizer firmware, and embeds a voltage-mode-control algorithm that maintains a tight output voltage between 11.88 V and 12.12 V and accurately controls the 20 millisecond ramp-up time.     

“Designing a product of this nature in a traditional way would require significant hardware modifications and could mean many months work,” said Patrick Le Fèvre, Marketing and Communication Director, Ericsson Power Modules. “However, the flexibility offered by the FRIDA II platform and its Ericsson Energy and Performance Optimizer firmware has made this possible in significantly less time, thereby reducing time-to-market for our customers. The BMR456 High-Cap Advanced Bus Converter is an excellent representation of the benefits offered by digital power and the unprecedented level of flexibility offered to board and systems designers.”    

Designed for 12 V bus applications that might only require 6 V in standby mode, controlled via PMBus commands, the output voltage of the BMR4560004/018 can also be adjusted to as little as 4 V, even powering 5 V board-level subsystems in idle mode, delivering significant headroom to board designers.     

The BMR4560004/018 has an output power of 420 W and a flat efficiency of