A first power line configured to receive a first voltage, a second power line configured to receive a second voltage which is lower than the first voltage, a first clamping unit configured to be connected to the first power line, a second clamping unit configured to be connected between the first clamping unit and the second power line, and a discharging unit configured to, when an abnormal voltage introduced through the first power line or the second power line is applied, discharge the abnormal voltage by coupling with the first clamping unit or the second clamping unit are included.