Isolated DC/DC converter targets next-gen data centres

Compact power modules from Flex Power Modules target the direct conversion market with its BMR481 DC/DC converter. It has an input range of 40 to 60V, targeting 48 to 54V nominal supplies, and a programmable 0.5 to 1.35V output.

The 12 x 27.7mm ‘main’ module provides a maximum output current of 70A and also incorporates a digital interface for monitoring, configuration and control purposes. This unit can be supported by up to five ‘satellite’ modules, for a total current rating of up to 420A.

The single-stage BMR481 is an alternative to the conventional two-stage intermediate bus converter (IBC) and point of load (PoL) architecture, which require an extra conversion step and needs more space. The direct conversion module is described by Flex as “groundbreaking”, being capable of achieving up to 92 per cent efficiency from a 1V output at 53V in; two to three per cent higher than an equivalent IBC-based deployment can deliver. It also allows a reduction in board area of up to 50 per cent, continues Flex. Mean time between failure (MTBF) is in excess of 8.7Mhrs for the main module.     

Automatic enabling and disabling of phases/satellite modules depending on the required load, contribute to the high efficiency. There is also dynamic voltage adjustment to provide optimum supply rails to connected ICs, explains Flex. Output ripple and noise is low, typically 1mV p-p, due to the zero voltage/zero current switching employed, explains the company. 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 degrees C ambient temperature with 0.5m/s airflow and to over 90 degrees 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 1500V DC (functional).

The BMR 481 is currently being sampled by key customers.