Electrostatic discharge (esd) protection circuit including an avalanche semiconductor controlled rectifier (scr) with parallel connected static trigger control circuit (tcc)

Abstract

A two terminal semiconductor controlled rectifier (SCR) device has an anode terminal coupled to a first node and a cathode terminal coupled to a second node. Neither of the cathode gate or anode gate of the SCR device are connected to a triggering circuit for controlling turn on of the SCR device. The SCR device has an avalanche breakdown voltage for turn on, where that avalanche breakdown voltage is set by a breakdown avalanche of a PN junction of the SCR device. A circuit path includes a series connected chain of M Zener diodes with a blocking diode that are coupled between the first node and the second node. The circuit path has an activation voltage for turn on, where that activation voltage is dependent on N times a Zener diode reverse breakdown voltage. The activation voltage is less than the avalanche breakdown voltage.