Communications Power

Digital POLs feature Dynamic Loop Compensation and Deliver Energy-Optimization

Ericsson Power Modules has introduced two new 3E (Enhanced Performance, Energy Management, and End-user Value ) dc-dc regulators to its family of BMR461 12 x 12 x 8mm digital point-of-load (POL) modules. The two new variants in the BMR461 family offer current outputs of 6A (BMR4612001) and 18A (BMR4614001) and join the existing 12A version (BMR4613001) launched toward the end of last year. Like the 12A BMR461 regulator, these two new modules also deliver Dynamic Loop Compensation (DLC), advanced energy-optimization algorithms to reduce energy consumption, low-bias current technology, and a land-grid-array (LGA) footprint that guarantees excellent thermal, mechanical and electrical performance.

An important feature of the two new modules is that they are 100 percent footprint compatible with the existing 12A BMR4613001 product. This means that customers will now have availability of these advanced POL regulators that offer three different output currents 6A, 12A and 18A while only having to handle a single module footprint in new systems. This significantly simplifies board design and makes it easier for power architects to move to higher or lower current-handling power modules without needing to redesign the system board when upgrading to new microprocessors or other advanced logic devices such as FPGAs or ASICs.

The 18A (BMR4614001) power module should prove of particular interest to power designers as it is optimized to deliver 18A at 1.8V, making it suited for processors operating at sub-2V core voltages. In fact, it is the first product of its kind to deliver this level of output current in a 12 x12mm footprint, while also delivering automatic loop compensation and full PMBus command capability.

"The launch of these two new 6A and 18A advanced POL modules is yet another demonstration of Ericsson's industry-leading design capabilities that provide advanced performance while simplifying the system design process when upgrading processors and shortening the time-to-market," said Patrick Le Fèvre, Marketing and Communication Director, Ericsson Power Modules. "Along with other advanced performance options, these new modules also offer Dynamic Loop Compensation circuitry like the 12A variant, negating the requirement for external components such as RC networks to adjust control loop compensation parameters."

The Dynamic Loop Compensation integrated into the 6A BMR4612001 and 18A BMR4614001 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 products perform an automatic compensation routine 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. Based on the 'state-space' mathematical model rather than traditional proportional-integral-derivative (PID) regulation, the devices use 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 used currently.

The 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.

The new modules feature 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, this combination of energy optimization algorithms and low bias technology requires up to five-times less current, and therefore further improves overall efficiency. Because of this combination, significant gains in efficiency can be made, 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 BMR461 modules power 0.6V applications at up to 85.7 percent efficiency at full load, whereas conventional units that are not using low-bias-current technology will have a typical efficiency of 75 percent. Or when operated from the 12V intermediate bus with the output set to 5V at 80 percent load, the modules deliver a typical efficiency of 96 percent.

Designed for high performance, the BMR461 modules recognize 84 PMBus commands and include a non-volatile memory allowing board-power-designers to upload their own configuration files. Easy synchronization is achieved through automatic pin detection and without the need for reconfiguration. In systems that use multiple BMR461s, the devices offer the ability to reduce EMI and the amount of input filtering through phase spreading via the PMBus INTERLEAVE command.

All three modules in the BMR461 family operate over a wide input voltage range 4.5V to 14.0V which makes the products 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 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 12×12 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 modules are 12.2 mm x 12.2 mm with a maximum height of 8.0 mm (0.48 x 0.48 x 0.315 inches) making them 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 magnetic technologies, as well as Ericsson's advanced manufacturing capabilities, the BMR461 family has an MTBF of 24 million hours. Other features include: 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.

Ericsson Power Modules AB
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