42-V Synchronous Buck DC/DC Controllers to Miniaturize Low-EMI Power Supply Size in Automotive Applications

Published  April 8, 2021   0
42-V Synchronous Buck DC/DC Controllers

The new DC/DC buck converters, LM25149-Q1 and LM25149 from Texas Instruments are designed with an integrated active EMI filter to enable engineers to achieve the smallest low-EMI power designs. With the help of these buck converters, designers can reduce the area of the external EMI filter by half, lower the conducted EMI of the power design by as much as 55 dBµV across multiple frequency bands, or achieve a combination of reduced filter size and low EMI. 

Featuring an integrated active EMI filter (AEF) and dual-random spread-spectrum (DRSS) technology, the LM25149-Q1, and LM25149 DC/DC buck controllers are the best suited for advanced driver assistance systems (ADAS), automotive infotainment and cluster, building automation, and aerospace and defense designs. These devices can 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. The DRSS technology helps mitigate EMI by an additional 5 dBµV across low- and high-frequency bands.

Additionally, both these devices feature frequency synchronization to an external clock, helping engineers to mitigate undesired beat frequencies in applications sensitive to EMI. The LM25149-Q1 and LM25149 controllers also help in increasing power density by enabling interleaved dual-phase operation and by integrating the bootstrap diode, loop compensation, and output-voltage feedback components, which in turn reduces design complexity and cost.

The Preproduction quantities of the 42-V LM25149-Q1 and LM25149 are available in a 3.5-mm-by-5.5-mm thermally enhanced, 24-pin very thin quad flat no-lead (VQFN) package from the company website only. The pricing starts at US$1.42 and US$1.20 in 1,000-unit quantities, respectively. Also, the LM25149-Q1EVM-2100 evaluation module is available for US$75. Multiple payment and shipping options are available. Both the devices will be available in volume production in the fourth quarter of 2021.