Since every switching power supply generates broadband noise, it is even more difficult to integrate the DC/DC converter in the automotive circuit board network into the automotive control device while meeting the EMC standards of the automotive OEM. .

Typically, noise from DC/DC converters and other high-speed circuits propagates and radiates through the connecting cables of the active antenna path. To block these potential radiation paths, noise needs to be filtered at each cable connection. This filtering is only effective if the magnetic and electric fields of the noise source are not coupled into the filter device or cable.

In a near-field environment, the drop in field strength is proportional to the inverse square of the distance (1/d2). Therefore, there must be a minimum distance between noise sources, filter components and connectors.

But in practice, the PCB size and the position of the cable connector are usually defined in advance according to the mechanical size. In addition, in some areas of the PCB, the height of the largest component may be very limited, and double-sided assembly may not be possible. At this time, the location of components and PCB routing need to be carefully laid out – especially for high-standard industries such as automobile manufacturing.

layout planning

In order to avoid directly coupling the electric field and magnetic field in the DC/DC converter into the connector and cable, the circuit must be arranged as far away from the PCB connection point as possible (see Figure 1).

Distance or additional shielding can reduce the field strength of EMC filters, connectors and cables. Consider using shielding instead of distance