In one embodiment, a power integrated circuit device is provided. The power integrated circuit device includes a high-side power switch having a high voltage transistor and a low voltage transistor. The high voltage transistor has a gate, a source, and a drain, and is capable of withstanding a high voltage applied to its drain. The low voltage transistor has a gate, a source, and a drain, wherein the drain of the low voltage transistor is connected to the source of the high voltage transistor and the source of the low voltage transistor is connected to the gate of the high voltage transistor, and wherein a control signal is applied to the gate of the low voltage transistor from the power integrated circuit device. The high-side power switch is turned on when a predetermined voltage is applied to the source of the low voltage transistor, a voltage higher than the predetermined voltage is applied to the drain of the high voltage transistor, and a voltage level of the control signal becomes higher than the predetermined voltage by a threshold voltage of the low voltage transistor.