Voltage regulator employs digital dynamic-loop-compensation

September 11, 2013 // By Graham Prophet
An advanced POL module enables designers to achieve high performance without compromising on dynamic response; Ericsson says it is the first auto-compensated digital point-of-load regulator based on ‘state-space’ or ‘model-predictive’ control, reducing cost and time-to-market while increasing flexibility.

Ericsson has introduced a new 3E* DC-DC regulator, the BMR461, that is 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-optimisation algorithms to reduce energy consumption, and a land-grid-array (LGA) footprint for thermal, mechanical and electrical performance.

The 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.

This, Ericsson says, removes the requirement for external components such as RC networks to adjust control loop compensation parameters, and as some board designs will employ 30 or even more 12A POL regulators, the BMR461 will simplify the design and maintenance process. 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 suitable for FPGA and processor applications where low-ESR decoupling capacitors are currently being used. It is designed to accommodate the majority of applications via PMBus commands.

The BMR461 claims 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