A quasi-analytical model addressed to predict the breakdown voltage in four-layer transient voltage suppressor (TVs) diodes based on the punch-through effect is reported in this paper. For breakdown voltage in excess of 1 V, a closed form expression is derived. In addition, the three-layer TVs diode can also be described with the developed model. Finally, results obtained from the model are in good agreement with simulation and experimental data. (c) 2005 Elsevier Ltd. All rights reserved.