Electrostatic protection circuit

An electrostatic protection circuit, comprising:

• a first power source line to which a first power source voltage can be applied;
• a second power source line to which a second power source voltage can be applied;
• a trigger circuit including a resistor and a capacitor connected in series between the first power source line and the second power source line, and configured to output a trigger signal from a connection node between the resistor and capacitor;
• a buffer circuit configured to output a drive signal in response to the trigger signal;
• a shunt transistor having a main current path connected between the first power source line and the second power source line, the drive signal being supplied to a control electrode of the shunt transistor;
• and
• a control circuit connected between the first power source line and the second power source line, and configured to electrically connect the control electrode of the shunt transistor to one of the first and second power source line in response to the drive signal.

An electrostatic protection circuit, comprising:

• a first power source line to which a first power source voltage is to be applied;
• a second power source line to which a second power source voltage is to be applied;
• a trigger circuit including a resistor and a capacitor connected in series between the first and second power source lines and configured to output a trigger signal in accordance with a voltage difference between the first and second power source lines;
• a buffer circuit including an input terminal connected to a connection node between the resistor and capacitor and configured to output a drive signal from an output terminal in response to the trigger signal;
• a switch circuit including a switch terminal connected to the output terminal of the buffer circuit and configured to switch an electrical connection between the first and second power source lines between an ON state and OFF state in response to a signal supplied to the switch terminal;
• and
• a control circuit connected to the switch terminal and configured to supply a control signal to the switch circuit in response to the drive signal, wherein
• when the trigger signal indicates a voltage difference between the first and second power source lines exceeds a first predetermine value, the drive signal from the buffer circuit causes the switch circuit to switch the electrical connection to the ON state and also causes the control circuit to supply the control signal to the switch terminal, and the control circuit is configured supply the control signal to maintain the electrical connection in the ON state while the voltage difference between the first and second power source lines exceeds a second predetermined value.