Flex moves to 48V direct conversion for data centre and cloud power
The company is aiming to be the leading supplier of such modules, with 48V-to-Load technology for next generation public and private data centres, starting with the BMR481 module.
“Direct Conversion will be pivotal in stopping data centre capital and operational costs from spiraling, as well as enabling increasingly stringent energy efficiency guidelines to be met,” said Olle Hellgren, Director Product Management and Business Development at Flex Power Modules. “This is being made possible by eliminating the 12V intermediate level conversion stage in order to boost efficiency, along with utilizing less board space. With the BMR 481, Flex is pushing forward the proliferation of Direct Conversion, and demonstrating the huge potential of this new power conversion architecture.”
The DC-DC converter has an input range of 40-60V targeting 48-54V nominal supplies, and a programmable 0.5-1.35V output. The 12 x 27.7mm footprint ‘main’ module provides a maximum output current of 70A and also incorporates a digital interface for monitoring, configuration and control purposes. This main unit can then be supported by up to 5 additional ‘satellite’ modules, resulting in a total current rating that reaches 420A and the main module has a mean time between failure (MTBF) over 8.7Mhrs, essential for data centres that have to be available at all times.
The key to direct conversion is to replace the two-stage intermediate bus converter (IBC) and point of load (POL) architecture. That extra conversion step takes up greater space and impacts the conversion efficiency. The single step module can reach 92% efficiency from a 1V output at 53V in, 2 to 3 percentage points higher than the equivalent IBC-based system and cut board area by half.
The efficiency comes from automatic enabling and disabling of phases/satellite modules depending on the required load, along with dynamic voltage adjustment to provide optimum supply rails to connected ICs. Output ripple and noise is extremely low, typically 1mV p-p, due to the zero voltage/zero current switching employed. Load and line regulation are typically kept to just 1mV. At 53V input and 0.5V output, the full 70A output current is available from the main module to over 75°C ambient temperature with 0.5m/s airflow and to over 90°C with just 2m/s airflow. Full digital control is implemented with a PMBus v1.3 interface compliant with PMBus or AVS / SVID. Isolation is rated at 1500VDC (functional).
The BMR 481 is currently being sampled by key customers.
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