PURPOSE: To obtain a monolithic IC highly resistant to static breakdown by providing a transistor with the collector connected to the input terminal, the emitter to the power supply and the base open.

CONSTITUTION: In an IC chip 10, a transistor QI is connected as specified to by- pass electrostatic energy applied on the input terminal depending on a breakdown characteristic between C and E with the base open. Since the breakdown point at the junction between C and E is lower than that between C and B and moreover, negative in the resistance, the voltage shows a considerably low value after the final breakdown. The action of the transistor continues after the breakdown resulting in a much lower impedance than the C-B junction. This minimizes the heating of the elements themselves to protect them from destruction and provides such a low impedance thereby enabling the formation of a monolithic IC highly resistant to electrostatic breakdown and with a large capacity of absorbing electrostatic energy. Grounding through a resistor from the base permits the absorption of variance in the CEO structure. The diode DI is a parastic element.