Integrated circuit with protection from transient electrical stress events and method therefor

An integrated circuit for protecting against transient electrical stress events comprising:

• a rail clamp device;
• a trigger circuit including:
• a resistive-capacitive (RC) filter;
• a drive circuit including a first inverter stage configured to receive an input signal from the RC filter, and to enable the rail clamp device during a transient electrical stress event;
• a stress event detection circuit coupled to the RC filter;
• the drive circuit having a configurable activation voltage which is controlled by the stress event detection circuit, wherein the activation voltage is reduced when the transient electrical stress event is detected;
• and
• an activation voltage adjustment circuit configured to generate an adjustment voltage to reduce the activation voltage when the transient electrical stress event is detected, wherein the activation voltage adjustment circuit includes:
• a first MOS transistor having a gate electrode coupled to a first output of the stress event detection circuit, a first current electrode coupled to a gate electrode of a second MOS transistor, and a second current electrode coupled to a first voltage supply net;
• the second MOS transistor further includes a first current electrode coupled to a second voltage supply and a second current electrode coupled to a first terminal of a ballast element in the drive circuit;
• a third MOS transistor having a gate electrode coupled to a second output of the stress event detection circuit, a first current electrode coupled to the gate electrode of the second MOS transistor, and a second current electrode coupled to the first terminal of the ballast element in the drive circuit.