Patent ID: 6621673
Filing Date: 2003-09-16
Classification: H01L

Abstract:
A two-stage electrostatic discharge (ESD) protection circuit, suitable to an input/output (I/O) port, coupled across a pad and a power rail, comprising:a primary ESD protection circuit, coupled between the pad and the power rail; an ESD detection circuit, coupled between the pad and the power rail; a resistor, connected in series between the pad and a internal circuit, wherein the ESD detection circuit is coupled to the internal circuit through the resistor; and a secondary ESD protection circuit, coupled between the internal circuit and the power rail; wherein, at the beginning of an ESD event, the ESD detection circuit provide a trigger voltage to trigger on the secondary ESD protection circuit prior to the activation of the primary ESD protection circuit, thereby clamping voltage received by the internal circuit.