Patent attributes
A protection circuit with suppressed erroneous operation due to power source fluctuation has a first resistor and a capacitor connected in series between a power source line and a ground line, an inverter with an input connected between the first resistor and the capacitor, and a MOS transistor with a gate electrode that receives an output of the inverter and with a drain electrode and source electrode connected to the power source line and the ground line. When high voltage fluctuation occurs in the power source line, a level change at a connection point between the first resistor and the capacitor is delayed according to a time constant. By the delay, the MOS transistor that receives an output of the inverter is temporarily turned on and discharges a high voltage to the ground line.
