Chip ferrite beads suppress power line noise in automobiles

In the automotive market, the need for noise suppression to counteract conductive and radiated noise has recently increased due to the development of motorisation of various functions including those in hybrid and electric cars.

For example, the number of motor control circuits (with brushes) or inverter circuits (brushless) has increased with the motorisation of powertrains, requiring noise suppression components that are capable of dealing with large currents.

Furthermore, in order to reduce vehicle weight - which is directly related to fuel economy improvement - the ECUs for engine systems and safety systems tend to be located in engine bays that reach high temperatures, and hence require noise suppression components capable of working in, and sustaining those high temperatures.

Murata has realised a product with the small package size of 3216 (3.2x1.6mm) that supports the large currents suitable for power lines (120ohm/4A at 125ºC) by creating design specifications for internal and external electrodes for use in environments of 150ºC, thus contributing to the creation of noise suppression designs for these power lines.

The BLM31KN_BH series conforms to the all-important automotive test standard AEC-Q200, and is available within the range of -55 to 150ºC with derating of the rated current; it determines the rated current at ambient temperatures of 125ºC and 150ºC and guarantees the specifications and reliability in environments of 150ºC. The beads’ impedance up to 1,000ohm is effective for noise suppression at 100MHz.