First advanced DC controller with integrated active EMI filter

Texas Instruments has introduced a new family of synchronous DC/DC buck controllers that enable engineers to reduce the size and electromagnetic interference (EMI) of power solutions. The LM25149-Q1 and LM25149 employ integrated Active EMI Filter (AEF) and dual Random spread frequency (DRSS) technologies that enable engineers to halve the area of the external EMI filter, reduce the conducted EMI of the power supply design by up to 55 dBµV across multiple frequency bands, or reduce the filter size and EMI simultaneously.

Reducing EMI in power supplies is a growing design challenge, especially with the increase in advanced driver assistance systems (ADAS), automotive infotainment systems and instrument packs, building automation, and electronics in aerospace and defense design. Previously, the way to ensure that the design met the conducted EMI specifications was to increase the size of the external passive EMI filter, which in turn increased the overall size of the power solution. With an integrated active EMI filter, the LM25149-Q1 and LM25149 step-down controllers enable engineers to meet EMI standards while increasing the power density of their designs. To learn how an integrated active EMI filter works, read the technical article "How to Reduce EMI and Reduce Power Supply Size with an Integrated Active EMI Filter."

Reduce conducted EMI across the spectrum involved in CISPR 25 Class 5

The CISPR 25 Class 5 standard of the International Special Committee on Radio Interference imposes stringent industry requirements for low EMI design in automotive environments. The LM25149-Q1 and LM25149 step-down controllers help engineers meet these requirements by reducing conducted EMI across multiple frequency bands. Integrated active EMI filters help detect and reduce conducted EMI in low-frequency bands from 150 kHz to 10 MHz, enabling engineers to reduce EMI by up to 50 dBµV (at 440 kHz switching frequencies, Compared to designs with AEF disabled) or 20 dBµV (compared to designs with typical passive filters). In both designs, DRSS technology helps reduce EMI by a further 5 dBµV in the low and high frequency bands.

To further reduce EMI, both step-down controllers operate at a synchronized frequency with an external clock, helping engineers reduce bad beats in EMI sensitive applications. To learn more about EMI reduction technologies, read the white paper "Reducing EMI in Power Supplies Through Innovative Technologies that Save Time and Costs."

Reduce the cost of the solution to a greater extent while shrinking the external EMI filter

In switching power supply designs, achieving low EMI power supplies and small solution sizes are often contradictory. The LM25149-Q1 and LM25149 step-down controllers enable engineers to meet challenging EMI standards and reduce solution size by reducing the area and volume of passive EMI filters. At 440 kHz, engineers can reduce the area and volume of the front-end EMI filter by up to nearly 50% and more than 75%, respectively, compared to comparable solutions. By reducing the filtering load on passive components, integrated AEF can reduce the size, volume, and cost of passive components, allowing engineers to achieve smaller, low-EMI power supply designs.

The LM25149-Q1 and LM25149 controllers further increase power density by implementing interleaving biphase operation and integrating bootstrap diodes, loop compensation, and output voltage feedback elements, thereby reducing design complexity and cost. Engineers can also use external feedback and loop compensation to further optimize their designs.