New Industry Products

Bourns Releases Industry First Planar BMS Signal Transformer

January 27, 2024 by John Nieman

Bourns expands its line with the industry’s first planar signal BMS transformer plus a high-current shielded power inductor. 

In a first for the industry, Bourns is harnessing the benefits of planar technology with the SM91806AL BMS Planar Transformer, which promises to increase design flexibility, safety, and efficiency for applications such as electric vehicles and industrial power supplies. 


Bourns SM91806AL BMS Planar Transformer.

Bourns SM91806AL BMS Planar Transformer. Image used courtesy of Bourns


Additionally, Bourns’ compact Model SRP3212 Series shielded power inductor is designed for use with DC-DC converters and battery chargers.


Technical Features of the BMS Planar Transformer

Planar technology eliminates many drawbacks of conventional wire-wound designs by increasing power density and exhibiting low parasitics

Bourns’ planar transformer brings cutting-edge technology to battery management system (BMS) design. With a working voltage of up to 1000 VDC and a robust Hi-Pot capability at 4300 VDC or 3000 VAC, this transformer improves reliability and safety. 


SM91806AL BMS Planar Transformer.   

SM91806AL BMS Planar Transformer. Image used courtesy of Bourns


SM91806AL also carefully adheres to strict regulations, including its basic insulation, which is compliant with  IEC 60664-1, IEC 61558-1, and IEC 62368-1. In addition, it is highly compatible and designed to seamlessly integrate with Analog Device’s LTC6815 series, NXP’s MC33771C series, and TI’s model BQ79616. 

The planar transformer is engineered with a minimum creepage distance of 8.2 mm, overvoltage category II, and supports partial discharge up to 1200 V per IEC 60664, demonstrating its high-quality construction.


Diagrams for the SM91806AL BMS Planar Transformer.

Diagrams for the SM91806AL BMS Planar Transformer. Image used courtesy of Bourns 


Because halogens tend to degrade air quality and can pose toxicity risks when disposed of, this Bourns’ planar transformer is halogen-free and RoHS compliant. 

Traditional design for transformers has developed into a mature sector of technology, so many clients will want to fall back on the dependability of conventional transformer tech, thus losing out on the planar advantages, but Bourns is increasing access to these advantages without compromising dependability.   


Specs for Model SRP3212-1R0MR21 Mini-molding High-Current Shielded Power Inductor

In addition to their innovative BMS planar transformer, Bourns is rolling out an addition to the Model SRP3212 series, a collection of high-current shielded power inductors

Unshielded inductors include an exposed coil, which can lead to an array of problems. In particular, the exposed coil design does not contain or inhibit electromagnetic fields. The shielded inductor adds a layer of safety and protection that inhibits electromagnetic interference (EMI).  

Bourns’ latest addition to its Model SRP3212 Series is also noteworthy for its smaller size. Even though shielded inductors offer reduced EMI, there is a performance tradeoff. Typically, shielded inductors are larger and have lower saturation, but Bourns’ shielded inductor is small enough for use in a smartphone. Model SRP3212-1R0MR21 measures 3.2 x 2.5 x 1 mm, and a more detailed dimension diagram can be seen below. 


Detailed dimensions for model SRP3212-1R0MR21

Detailed dimensions for model SRP3212-1R0MR21. Image used courtesy of Bourns


This shielded inductor features a metal alloy powder core for high saturation current, and it has been created to be compatible with Texas Instruments Model BQ25638/BQ25638D.