Switching Power Supplies A - Z

CHAPTER

12

Fixing EMI across the Board

1-oz (okay 2-ounces!) of prevention are always better than cure. So here we look at some of

the practical design aspects involved in controlling and testing EMI.

The Role of the Transformer in EMI

Very often an engineer resolves a stubborn EMI problem by just ‘playing’ with the

transformer. The transformer comes into the picture in the following ways:

■

With its windings carrying high-frequency current, it becomes an effective H-field

antenna. These fields can impinge upon nearby traces and cables, and enlist their

help in getting transported out of the enclosure, via conduction or radiation.

■

Since parts of the windings ...