Designing with Microcontrollers with Low EMI

This paper describes the results of Intel Automotive's recent experiments for designing systems for low electromagnetic interference (EMI) using the MCS® 96 microcontroller family. The experiments focused on several configurations of a “representative” ABS module. The objectives were to study a layout technique called “micro-island”, various grounding techniques, and the EMI benefit of 4 layer printed circuit boards (PCB) boards over 2 layer PCB boards. The tests showed: the wiring harness is a large contributor to the system emissions, the “micro-island” technique provides significant EMI reduction, and 4-layer PCB designs perform significantly better than 2-layer PCB's. In addition, it was demonstrated how poor layout can lower the performance of a 4-layer PCB to that of a 2-layer PCB.