At the Electronics Goes Green (EGG) congress held recently Ericsson presented the use of advanced dynamic bus voltage architectures as a way to minimize energy expenditure at the board level.
Today, the standard power architecture increasingly being used is the Intermediate Bus Architecture (IBA), which uses intermediate bus converters (IBCs) to convert a traditional 48 VDC distribution-level power line used in telecoms to typically a static 12 VDC. This first ‘down-conversion’ 12V level feeds a number of DC/DC point-of-load (POL) regulators, which supply the final load voltages at a chip’s logic supply levels of 3V or below. The choice of 12 VDC 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 dynamic bus voltage (DBV) architecture is an evolution of the IBA and provides the possibility to dynamically adjust the power envelope to meet load conditions. It achieves this by adjusting the intermediate bus voltage, previously the 12 VDC 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.
“Dynamic Bus Voltage is a technology that makes possible to reduce board power consumption from anywhere between 3 and 10 percent, depending on the board application,” said Patrick Le Fčvre, Marketing and Communication Director, Ericsson Power Modules. “The potential for energy saving is a very substantial one, especially when taking into account the fact that 1W saved at the board level can result in a 3W saving at the power grid level.”
To that end, Ericsson 3E BMR456-DBV and BMR457-DBV advanced bus converters feature the ‘Ericsson DC/DC energy optimizer’ firmware – implemented in ARM microprocessor technology – which enables a significant contribution to the reduction of power consumption, according to Ericsson.
The output voltage of the quarter-brick BMR456-DBV can be adjusted within an operation range of 13.0V to 8.2V, and then down to 4V to power ultimate below 5V Sleep Mode configuration, which today requires an extra power module.
Designed for smaller systems, the eighth-brick-format BMR457-DBV full operational output voltage is optimized for 13.2V to 8.2V adjustment, and then can be adjusted down to 6.9V, making it possible to power the mid-power range of applications requiring 6V Sleep Mode configuration.
In both products, the output voltage can be adjusted via PMBus commands or preset profiles stored by the system designer in the built-in USER_STORE memory block, making it simple to adjust the intermediate board bus voltage to a level that will guarantee the lowest power consumption, according to Ericsson.
The Ericsson DC/DC energy optimizer is able to handle input voltage transients with slew-rates up to 0.5 V/µs, while keeping the output voltage within +/-10 percent. This ensures that the output voltage does not trigger over-voltage protection, according to the company.
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