A power conversion system includes, for example, a PFM controller, a PWM controller, and an auxiliary voltage output stage. The PFM controller controls a power output stage in a PFM mode in response to a power stage voltage output generated by the power output stage during a first period of time in which the power output stage is operating in the PFM mode. The PWM controller controls the power output stage in a PWM mode in response to a power stage voltage output generated by the power output stage during a second period of time in which the power output stage is operating in the PWM mode. The auxiliary voltage output stage generates an auxiliary voltage during a third period of time, where the PWM controller controls the auxiliary power output stage using the auxiliary voltage during the third period of time.