A regulator device includes a first switch, a second switch, and a controlling circuit. A control terminal of the first switch is configured to receive a first control signal. A first terminal of the second switch is coupled with a second terminal of the first switch at a node. A control terminal of the second switch is configured to receive a second control signal. The controlling circuit is coupled to the control terminal of the first switch, the control terminal of the second switch, and the node. The controlling circuit outputs the first control signal with a first slope to the first switch during a first period, and outputs the first control signal with a second slope to the first switch during a second period. The first period is less than the second period, and the first slope is larger than the second slope.