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. The EMI is most relevant at the switch mode power supply fundamental switching frequency 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.

For the MCP16369, the switching frequency will vary above the 2.2 MHz by +10% to reduce the EMI peak.