Patent ID: 9142953
Filing Date: 2015-09-22
Classification: H02H

Abstract:
1. An electrostatic discharge (ESD) protection apparatus, comprising: a clamp circuit, coupled between a first rail line and a second rail line, the first and second rail lines respectively having a first reference voltage and a second reference voltage; and a detection circuit, comprising: a first node; an electronic element, coupled between the first node and the second rail line, having an equivalent capacitance value; and a transistor, coupled to the first node; wherein, in response to an ESD event triggered between the first and second rail lines, a plurality of leakage currents correspondingly pass between a first input and a gate and between a second input and the gate of the transistor, and respectively in equivalence form a first parasitic resistance and a second parasitic resistance between the first input and the gate and between the second input and the gate; the first parasitic resistance and the second parasitic resistance and the electronic element form a delay circuit to provide a drive voltage between the gate and the first input for conducting the transistor, and to provide a trigger current for conducting the clamp circuit, so that the first and second rail lines perform an ESD operation via the clamp circuit, and the detection circuit further comprises: a second node and a third node, respectively coupled to the second input and a drive terminal of the clamp circuit; and a level limiting circuit, coupled between the second and third nodes, for determining a conducting voltage, disconnecting the second input from the drive terminal when a cross voltage between the second input and the drive terminal is lower than the conducting voltage, and connecting the second input to the drive terminal when the cross voltage is greater than the conducting voltage, wherein the conducting voltage is associated with a supply voltage.