Abstruct -Transient voltage suppressors are semiconductor devices used to clamp transients and save the equipment from excessive voltage spikes. The problem with these devices is that the protection voltage increases with the duration and amplitude of the trandent. This paper presents a SPICE model that permits the calculation of the protection voltage increase for different overvoltage wave shapes. The model h an effident tool to evaluate transient suppressor performance. 0-7803-0982-0/93 $3.00 1993 IEEE