Circuit protection method using diode with improved energy impulse rating

Abstract

A method for protecting a circuit from a high energy pulse includes placing a PPTC resistive element in series with the circuit and placing an energy pulse clamping semiconductor diode in shunt across the circuit and further includes forming the diode to have: a substrate with carriers of a first type of conductivity in a first, high concentration level (e.g. n++), a first major face and a second major face opposite to the first major face; a layer of semiconductor material having carriers of the first type of conductivity in a second concentration level lower than the first level (e.g. n+), and an outer surface; a region formed at an outer surface having carriers of a second type of conductivity in a third concentration level (e.g. p+); at least one cell having carriers of the second type of conductivity in a fourth concentration level greater than the third concentration level (e.g. p++); and, a cathode electrode and an anode electrode. In the method, the diode region becomes a second-level bi-directional intrinsic conduction region as an intrinsic temperature of the region is approached in response to thermal energy initially generated at the diode cell in response to the high energy electrical pulse. The method includes thermally coupling the diode to the PPTC resistive element to accelerate trip thereof in response to the high energy electrical pulse.