Patent ID: 7283342

Claim:
A power-rail ESD clamp circuit with high-voltage tolerant capability comprising: an ESD detection circuit connected to at least a voltage source and a ground terminal and used to detect whether there is ESD between said voltage source and said ground terminal, said ESD detection circuit further comprising: a voltage divider including a plurality of p-type transistors to split an input voltage of said voltage source into two divided voltages; a substrate driver connected with said voltage divider and used to drive a substrate to produce a trigger current, said substrate driver including a first transistor, a second transistor and a third transistor, a first node being located between said first transistor and said second transistor, said third transistor being connected to a trigger node; an RC distinguisher including a first resistor and a capacitor, one end of said first resistor being connected to said first node, and another end being connected to a gate of said second transistor and said capacitor to form a second node; a fourth transistor connected to said substrate driver via said trigger node and to said RC distinguisher via a third node; and a second resistor with one end connected to said third node and another end connected to a low voltage source; an ESD protection element triggered on via said trigger current of said trigger node by said ESD detection circuit to quickly and uniformly discharge an ESD current in an ESD situation.