An electrostatic discharge device includes a power clamping circuit and an isolation circuit. The power clamping circuit includes a first Zener diode and a second Zener diode. A cathode of the first Zener diode is coupled to a first power supply line. An anode of the first Zener diode is coupled to an anode of the second Zener diode. A cathode of the second Zener diode is coupled to a second power supply line. The isolation circuit includes a first isolation diode and a second isolation diode. A cathode of the first isolation diode is coupled to the first power supply line. An anode of the first isolation diode is coupled to a cathode of the second isolation diode and a circuit being protected. An anode of the second isolation diode is coupled to the second power supply line.