Electrostatic breakdown preventing circuit for semiconductor device

摘要

An electrostatic breakdown preventing circuit has first and second conductive lines, a diode, a power clamp circuit and first and second capacitors. The first and second conductive lines are connected to a first potential source and a second potential source, respectively. The internal circuit is connected between the first and second conductive lines. The internal circuit operates in response to an input signal. The diode is connected in a forward direction between an input terminal and the second conductive line. The first capacitor is connected between the node and the first conductive line. The second capacitor is connected between the node and the second power conductive line. The capacitances of the first and second capacitors are set in such a manner that the transistor is brought to an OFF state upon a normal operation and brought to an ON state upon the input of an electrostatic surge.