Switching-Mode Power Supply Entrainment (2 of 7)

Relevance

Autonomous circuits (no external driving function) such as a ripple regulators, hysteretic converters, etc., are far more susceptible to this problem than driven circuits. In fact, changing an autonomous circuit topology to a clock-driven circuit topology is often the solution. However, driven circuits such as PWM converters, can also be susceptible and need to be tested. Not synchronizing the power supply frequency to the system clock frequency can also aggravate the problem due to increased beat frequencies.

Solvability

This is a non-linear phenomena. To the extent that it can be solved analytically for any given circuit, the analysis is complex to the point of being impractical for most projects. The same could be said to apply to simulation. The only practical solutions is to test a circuit for the phenomenon, and if induced, fix the circuit and make sure that the inducing conditions can never occur in the system.

Do not use this information for design without independent verification of the information.

Editor: Jerrold Foutz