In accordance with an embodiment, a method of operating a switched-mode power supply includes starting up the switched-mode power supply by applying a first switching signal to a control node of the first switching transistor and a second switching signal to a control node of a second switching transistor, where a duty cycle of the first switching signal is less than a duty cycle of the second switching signal. After starting up the switched mode power supply, the switched mode power supply is operated by applying a third switching signal to the control node of the first switching transistor and a fourth switching signal to the control node of the second switching transistor, where a duty cycle of the third switching signal is substantially equal to a duty cycle of the fourth switching signal.