DBV architecture saves power in datacenters

The increasing demand for more internet services and cloud computing is driving both the expansion and building of new datacenters around the world. A key challenge for operators is the minimization of energy expenditure at the board level. A significant aid to this process is the use of advanced DBV (dynamic-bus-voltage) architectures. Today, the standard power architecture increasingly being used is the IBA (intermediate-bus architecture), which uses IBCs (intermediate-bus converters) to convert a traditional 48 V DC distribution-level power line used in telecoms to typically a static 12 V DC. This first down-conversion 12-V level feeds a number of POL (point-of-load) DC-DC regulators, which supply the final load voltages at a chip's logic supply levels of 3 V or below. The choice of 12 V DC has been made to ensure a high enough voltage to deliver all the power required by the board, or load, in times of high data traffic. However, this approach becomes highly inefficient when the traffic demand is low. The DBV is an evolution of the IBA and provides the possibility to adjust dynamically the power envelope to meet load conditions. It achieves this by adjusting the intermediate bus voltage, previously the 12 V DC fixed bus voltage, via the use of advanced digital power control and optimized hardware combined with an energy-optimizer series of algorithms. This can lead to reductions in both energy consumption and power dissipation, which in turn contributes to a reduction in the amount of cooling that is required. DBV is a technology that makes possible to reduce board power consumption from anywhere between 3% and 10%, depending on the board application. The potential for energy saving is a very substantial one, especially when taking into account the fact that 1 W saved at the board level can result in a 3 W saving at the power grid level. Converters for the DBV architecture can be adjusted within an operation range of 13.0 to 8.2 V and adjusted further down to 4 V to power below-5-V sleep modes, which today requires an extra power-module. The energy optimizer not only optimizes switching parameters to reduce energy consumption, but also offers features including the ability to handle input voltage transients with slew-rates up to 0.5 V/μs, while keeping the output voltage within ±10%. This ensures that the output voltage does not trigger over-voltage protection. It also very efficiently manages pre-bias start-up operation and shut down is fully controlled avoiding voltage spikes that cause avalanche conditions in the secondary-side synchronous rectification MOSFET, making a contribution to further improve reliability. Ericsson Power Modules