Patent ID: 7616415

Claim:
An electrostatic discharge (ESD) protection circuit that prevents ESD caused by an internal circuit supplied with a power voltage and different first and second ground voltages respectively provided from a power pad and first and second ground pads to operate the internal circuit, comprising: a first ESD protector connected between the power pad and the second ground pad so as to provide a first ESD path between the power pad and the second ground pad; a second ESD protector connected between the first and second ground pads to provide a second ESD path between the first and second ground pads; and a third ESD protector connected between the power pad and the first ground pad and configured to make driving voltages of the first and second protectors become lower than a gate oxide breakdown voltage of elements in the internal circuit by providing a third ESD path, wherein, during an ESD test, if the sum of the driving voltages of the first and second ESD protectors is higher than the gate oxide breakdown voltage of the elements in the internal circuit or if the current flowing at the time when the first ESD protector starts its operation and the voltage drop caused by a line resistor connected to the power pad is higher than a value obtained by subtracting the driving voltages of the first and second ESD protectors from the gate oxide breakdown voltage of the elements in the internal circuit, the third ESD protector is connected between the power pad and the first ground pad.