Investigation of SPICE Models for Overvoltage Protection Devices With Respect to Fast Transients

Abstract

Models of overvoltage protection devices, such as transient voltage suppressor diodes (TVS-diodes) are largely available in circuit analyzer tools. For this letter, the widely used circuit simulation tool LTspice was employed and during the course of investigating the simulation of such protection devices in the context of electrical fast transient phenomena, especially electrical fast transients (EFT/BURST) and electrostatic discharge (ESD), certain existing diode-model types can present inaccuracies when predicting the disturbances generated by those devices. Presumably this is the case regarding the model of the junction capacitances, especially for the cutoff region, since the implementation follows a linear extrapolation and therefore differs from the real behavior of the protection device under test. This letter deals with the investigation of a simulation setup and occurring limitations for the analysis of the transient behavior. It should give some encouragement to always consider given model-limitations and how they can affect the simulated results and also if the applicability for certain investigations is provided.