Date
09/27/2013
PDF
Ericsson has introduced a new 3E* DC-DC regulator, the BMR461, presented as the first 12 x 12 x 8mm 12A digital point-of-load (POL) module to combine Dynamic Loop Compensation (DLC), low-bias current technology, advanced energy-optimization algorithms to reduce energy consumption, and a land-grid-array (LGA) footprint that guarantees excellent thermal, mechanical and electrical performance. Dynamic Loop Compensation The new BMR461 Dynamic Loop Compensation is based on ‘state-space' or ‘model-predictive' control, which guarantees stability while also achieving the optimum dynamic performance without requiring any external components. The new product performs an automatic compensation routine that is based on measured parameters, which enables the construction of an internal mathematical model of the power supply including external components such as filtering and parasitic resistors. "The Dynamic Loop Compensation circuitry built into the BMR461 negates the requirement for external components such as RC networks to adjust control loop compensation parameters," said Patrick Le Fèvre, Marketing and Communication Director, Ericsson Power Modules. "As some board designs will employ 30 or even more 12A POL regulators, the BMR461 will significantly simplify the design and maintenance process for power designers. Furthermore, when considering the board-space and time that is usually required for conventional technology to test and verify loop-stability of each module, the BMR461 represents significant savings both in terms of cost and time while also improving reliability." Based on the ‘state-space' mathematical model rather than traditional proportional-integral-derivative (PID) regulation, the BMR461 uses closed-loop pole placement and a model based on the resonant frequency of the output filter, thereby reducing the number of output capacitors required for filtering and stability. This technology is highly suitable for FPGA and processor applications where low-ESR decoupling capacitors are currently being used. The BMR461 DLC is designed to accommodate the vast majority of applications via PMBus commands. Board-power designers can therefore tailor the loop compensation; for example in low output voltages to enhance the recovery time at load release by enabling a negative duty-cycle using the LOOP_CONFIG PMBus command. Many other parameters can be simply adjusted and monitored without any hardware modifications. Optimized Efficiency The BMR461 features several algorithms that optimize efficiency across a wide range of operating conditions. Compared to the conventional technology that is currently implemented in analog and digital-hybrid POL regulators, the device's combination of energy optimization algorithms and low bias technology requires up to five times lower current, and therefore further improving overall efficiency. Because of this combination, the BMR461 makes significant gains in efficiency, especially in sub-1V modules where it performs up 10 points higher than high-market-average units. For example, taking power from a 5V intermediate bus, the BMR4613001 designed to power 0.6V applications reaches up to 85.7% efficiency at full load, whereas conventional units that are not using low-bias-current technology will have a typical efficiency of 75%. Or when operated from the 12V intermediate bus with the output set to 5V at 80% load, the BMR461 delivers 96% efficiency. PMBus Control Designed for high performances, the BMR461 recognizes 84 PMBus commands and includes a non-volatile memory allowing board-power-designers to upload their own configuration files. The BMR461 also includes easy synchronization through automatic pin detection and without the need for reconfiguration. In systems that use multiple BMR461s, the device offers the ability to reduce EMI and the amount of input filtering through phase spreading via the PMBus INTERLEAVE command. The BMR461 operates over a wide input voltage range - 4.5V to 14.0V - which makes the product suitable for the most common bus voltages in intermediate-bus architecture systems, such as 5, 8 and 12V, and therefore reduces the number of modules required to carried in inventories. The output voltage can be adjusted from 0.6V to 5.0V by a strap-resistor or via the VOUT_COMMAND PMBus command. The BMR461 also features: pre-bias start-up and shut-down; monotonic and soft-start power-up; input under-voltage shutdown; over-temperature protection and power-good; output short-circuit and over-voltage protection; remote control and differential sense; voltage setting via pin-strap or PMBus; and an advanced set of configurations via the Ericsson DC/DC Digital Power Designer software. Reliable FootprintM The BMR461 footprint is based on a matrix Land Grid Array (LGA) composed of 32 solder-pads and has been developed to meet OEM manufacturing requirements in terms of pick-and-place, solderability and co-planarity, or future evolutions such as high power devices with 12x12 footprints as well as additional features that require more interface pads. The use of LGA technology guarantees that each solder-pad will have an equal mass of solder providing excellent co-planarity. In addition, to reduce power losses each output is connected to six pads and the input uses four pads. Overall dimensions of the BMR461 are 12.2 x 12.2 with a maximum height of 8.0mm (0.48 x 0.48 x 0.315 inches) making the device suitable for use in low-board-pitch applications such as radio-controller cards. And as result of the low-bias-current technology combined with very advanced silicon and magnetics technology, as well as Ericsson's advanced manufacturing capabilities, the BMR461 has an MTBF of 11 million hours. A development board - called the ROA17003 - is also available to assist power system designers. It offers the ability to connect to other Ericsson 3E development boards that host digitally controlled Advanced Bus Converters (ABCs) and 3E Point-of-Load (POL) converters and create a complete solution prior to implementation within the final application. The BMR461 is priced at $8.70 in OEM quantities. Ericsson
