A pseudo-constant portion of a switching cycle (ON time or OFF time) is constant over short periods of time but the pseudo-constant portion is controlled over longer periods of time in a slow frequency control loop to maintain a desired frequency. The average frequency is maintained at or near a desired frequency but when there is a transient, local disturbance, or load change, or other occurrence, then for a short period of time the frequency will vary as the non pseudo-constant portion of the switching cycle changes to address the transient or other occurrence. The frequency control loop will slowly adjust the pseudo-constant portion of the switching cycle to return to the desired frequency.