Simulation Method to Evaluate Thermal Runaway of MOSFETs

The goal of this paper is to introduce a new simulation method using accurate models in order to evaluate the risk of the thermal runaway when MOSFETs are operating in the linear region: high drain to source voltage and high drain current simultaneously. We have applied to the models used in our simulation the theory mentioned in various papers from references. A behavioral electrothermal MOSFET model, written in MAST^®, was developed “in house” and used for the design as alternative to high complex models which require a huge effort for parameter extraction and to the limited number of MOSFET models available with tolerances for the models parameters which are reflecting the min-max limits and not only the typical behavior. Model temperature behavior is dynamic, covering the self-heating effect. The junction temperature is continuously calculated according with the dissipated power, thermal network and ambient temperature response.