Modeling the Electrothermal Stability of Power MOSFETs During Switching Transients

摘要

This letter investigates the electrothermal stability of MOSFETs during switching transients. Switch-mode MOSFETs, when transiting between the opposite ends of the load line, pass through bias conditions with high thermal runaway probability, i.e., $R_{rm TH} cdot V_{rm DS} cdot dI_{rm DS}/dT > hbox{1}$. It is shown here that the likelihood of thermal runaway increases when $dI_{rm DS}/dT$ is positive and the switching duration is greater than the thermal time constant. This condition is worse for advanced MOSFETs with high transconductance because the zero-temperature-crossover point occurs at higher drain currents. This letter uses a physically calibrated MOSFET model for detailed analysis of the electrothermal dynamics during switching transients.