A voltage control device includes a first charge pump, a first power switch, a second charge pump, a second power switch, and a third power switch. The first charge pump generates a first application voltage according to the first system voltage. The first power switch has a first input terminal for receiving the first system voltage, a second input terminal for receiving the first application voltage, and an output terminal. The second charge pump generates a second application voltage according to a voltage received by the input terminal of the second charge pump. The second power switch has an input terminal for receiving the second application voltage, and an output terminal. The third power switch has a first input terminal coupled to the output terminal of the first charge pump, a second input terminal coupled to the output terminal of the second charge pump, and an output terminal.