TI Releases DC/DC controllers that Enable Smaller, Lower EMI Power Systems

By Rich Nass

Executive Vice President

Embedded Computing Design

April 07, 2021


(Image courtesy of Texas Instruments)

The term “size matters” definitely applies when it comes to power electronics.

Components for this segment are typically big and bulky, and don’t often run “clean.” A series of DC-to-DC controllers released by Texas Instruments is poised to change that dynamic. The company claims that its new family of synchronous buck controllers enable designers that are about half of what is currently offered, and at the same time, considerably reduce the EMI, by as much as 55 dBµV across multiple frequency bands.

The LM25149-Q1 and LM25149 feature an integrated active EMI filter (AEF) and dual-random spread-spectrum (DRSS) technology. Such advances are welcome in the automotive space, particularly for advanced driver assistance systems (ADAS) and automotive infotainment and cluster, as well as building automation, and aerospace and defense designs.

The controllers help engineers meet the CISPR 25 Class 5 automotive EMI requirements by mitigating conducted EMI across multiple frequency bands. The integrated AEF helps detect and reduce conducted EMI in the low-frequency band of 150 kHz to 10 MHz, enabling engineers to attenuate EMI by up to 50 dBµV at a switching frequency of 440 kHz, relative to a design with the AEF disabled, or as much as 20 dBµV when compared to a design with a typical passive filter. In both design scenarios, the DRSS technology helps mitigate EMI by an additional 5 dBµV across low- and high-frequency bands. To further reduce EMI, both buck controllers feature frequency synchronization to an external clock, helping to mitigate undesired beat frequencies in applications sensitive to EMI.


Preproduction quantities of the 42-V LM25149-Q1 and LM25149 are available now, in a 3.5- by 5.5-mm thermally-enhanced, 24-pin VQFN package. Prices start at $1.42 and $1.20 in 1000-unit quantities, respectively. The LM25149-Q1EVM-2100 evaluation module is available for $75. Both devices should be available in volume production in the fourth quarter of this year. In addition, pin-compatible 80-V versions of both devices are expected.

Richard Nass’ key responsibilities include setting the direction for all aspects of OSM’s ECD portfolio, including digital, print, and live events. Previously, Nass was the Brand Director for Design News. Prior, he led the content team for UBM’s Medical Devices Group, and all custom properties and events. Nass has been in the engineering OEM industry for more than 30 years. In prior stints, he led the Content Team at EE Times, Embedded.com, and TechOnLine. Nass holds a BSEE degree from NJIT.

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