TI is the industry's first DC / DC controller with integrated active EMI filter, enabling the smallest low EMI power supply design.

Texas Instruments (TI) is the industry's first DC / DC converter with an integrated Active Electromagnetic Interface (EMI) Filter (AEF) to help engineers design minimal power solutions with low electromagnetic interference (EMI). Insisted on a DC controller. In addition to the integrated AEF, the new family of synchronous DC / DC buck controllers, the LM25149-Q1 and LM25149, incorporate dual random spread spectrum (DRSS) technology to help mitigate EMI.

There are some new scenarios LM25149-Q1 And LM25149 DC / DC controllers assist power designers. According to TI, these devices can cut the area of ​​the external EMI filter in half and reduce the conducted EMI of the power design to 55 dBµV over multiple frequency bands, or combine filter size reduction with low EMI. ..

The integrated AEF reduces the size, volume, and cost of passive EMI filters by reducing the filtering load on passive elements, enabling engineers to achieve the lowest possible low EMI power design. TI says.

Ganesh Srinivasan, TI Product Line Manager for Wide VIN Step-Down Switching Regulators, said that both active EMI filters and DRSS are built on the company's previous pseudo-random innovations to improve the performance of new devices and deliver 55 dBµV. He said it was a breakthrough technology that made it possible. Improved performance.

It is possible to maintain the same performance and reduce the size of the filter, "added Srinivasan. "The advantage is that you can reduce these bulky sizes. [passive] EMI filters in the system increase area by up to 50% and volume by 75%. Both of these have been significantly reduced from their current state. "

(Image: Texas Instruments)

One of the challenges faced by many OEM designers is as electronic content grows, especially in applications such as Advanced Driver Assistance Systems (ADAS), automotive infotainment and clusters, building automation, aerospace and defense design. , Is to reduce the power supply EMI.

Cecelia Smith, TI's Vice President and General Manager / Boost and Multi-Channel DC / DC, said:

She added that meeting EMI industry standards and reducing conduction and radiation emissions are important precautions for engineers designing power systems for automotive and industrial applications.

"Therefore, TI's approach to helping engineers tackle EMI challenges has two sides. First, designers can reduce the size, number of components, and cost of passive filters. The second is to be able to reduce the size of low EMI power supply designs. Second, innovations such as integrated bypass capacitors and integrated active EMI filters reduce design time and complexity, "says Smith. I will.

The most stringent industry requirements for low EMI design are the Comité International Spécial des Perturbations Radioélectriques (CISPR) 25 Class 5 Automotive EMI Specifications. Traditional methods used to ensure that the design meets conduction EMI specifications include increasing the size of the external passive EMI filter, which increases the overall size of the power supply solution.

These new DC / DC controllers help meet these requirements by reducing conducted EMI across multiple frequency bands. " Integrated AEF Helping to detect and reduce conducted EMI in the low frequency band 150 kHz to 10 MHz, engineers can attenuate EMI up to 50 dBµV at 440 kHz switching frequencies compared to designs with AEF disabled. I can do it. Compared to a typical passive filter design, it's 20dBµV, "says TI.

The device also uses add EMI mitigation technology Further reduce EMI. In any of the above design scenarios, DRSS technology helps reduce EMI by an additional 5 dBµV in the low and high frequency bands. The buck controller also features frequency synchronization to an external clock, further reducing EMI by reducing unwanted beat frequencies in EMI-sensitive applications.

Other features that help increase power density include interleaved two-phase operation, bootstrap diode integration, loop compensation, and output voltage feedback components, reducing design complexity and cost. TI said engineers have the option of further optimizing the design using external feedback and loop compensation.

According to Srinivasan, an evaluation module with a full-fledged user guide is available to help power designers easily evaluate parts. "EVM is configured to maximize the performance of the device, so you can test low I.Q Improvements in performance and both types of EMI, "says Srinivasan.

"At the same time, the customer E2E ForumTherefore, these tools can help power supply designers get the full performance out of their components, "he added.

Main features of LM25149-Q1EVM-2100 The evaluation module includes an input voltage range of 6 V to 36 V, an output voltage of 5 V with a set accuracy of 1%, a load current of 8 A, ultra-low IQ, DRSS and active EMI filtering. The evaluation module is available on TI.com for $ 75.

Prototype quantities of the 42-V LM25149-Q1 and LM25149 are currently available only at TI.com in a 3.5 x 5.5 mm heat-enhanced 24-pin ultra-thin quad flat no-lead (VQFN) package. Prices start at $ 1,000, starting at $ 1.42 and $ 1.20, respectively. Mass production is scheduled for the fourth quarter of 2021. TI plans to introduce a pin-to-pin compatible 80V version of both devices.

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