ABSTRACT
Switch Mode Power Supplies (SMPS) are normally one of the biggest generators of noise. The SMPS generates two types of noise: common mode and differential mode. Common mode noise occurs simultaneously on both lines of a conductor pair with respect to a common ground chassis, whereas differential noise occurs between the input conductor paths. The common mode noise occurs simultaneously on both lines of the input conductor pair with respect to a common ground. The main source of common mode noise in the SMPS is the stray capacitance to chassis ground that can be found in switching power transformer, inductors, transistors and diodes connected to the heat sink and any wiring carrying high ac currents. The primary noise generators that couple noise into the chassis are transistors and diodes. The alignment spacer helps provide a tight control of the windings space and provides a good control of the parasitics.
