TDK's ACT1210R series common‐mode filter is used as an EMC countermeasure in FlexRay networks. In order to respond to a market need to save space in ECU circuit boards, the ACT1210R series was developed, reducing mounting area by over 40% as compared with existing product. Typically, reducing component size would impact the common‐mode filter’s characteristics, however, TDK has adapted new technologies for the structure and a new core material. The ACT1210R series is a compact product with characteristics that are equivalent to that of conventional sized product (ACT45R series). The ACT1210R common‐mode filter maintains a common‐mode inductance of 100 μH with a DC resistance of less than 1.5 Ω.