A robust design method for MOSFET degradation in SMPS

Switching mode power supply (SMPS) plays a key role in electronic systems as a power source. Its reliability critically affects the lifetime of systems. The fundamental reason of system failure is component degradation and parameter drift due to the effects of various environmental conditions and operating stress. Therefore, the quality of SMPS can be improved by optimizing the component performance under stress. To evaluate component degradation, the time-to-degradation-failure (TTDF) may be employed as an indicator. In this paper, a robust design method based on TTDF is presented to extend the lifetime of components and to reduce the dispersion of components´ TTDF simultaneously. To reveal the relationship between stresses and degradation, the impact of stress on degradation is analyzed and the model of TTDF induced by the major failure mechanisms is established. This method is demonstrated by a case study of MOSFET´s heat sink. Finally, the optimized result is compared to the initial parameters through Monte Carlo simulation while considering uncertainty in stochastic variables.