5.12 Frequency Dithering

When designing a DC-DC switching power supply, one of the challenges that must be overcome is controlling the electromagnetic interference (EMI) emissions produced during normal operation. EMI is most significant at the fundamental switching frequency of the switch-mode power supply and is reduced for each higher order harmonic. To decrease this peak emission, modulating or dithering the switching frequency is used so that the EMI is spread over a band of frequencies.

In the MCP16369, the switching frequency is varied by +10% above the nominal 2.2 MHz help lower EMI peak levels.