Ruggedness Evaluation of Low Voltage Trench MOSFET against Repetitive Avalanche

It is widely known and accepted that virtually all power MOSFET datasheets have well-defined single pulse avalanche performance. However, the repetitive avalanche performance of MOSFETs is usually not specified in the datasheet. In many power conversion applications such as regulators, power supplies and automotive fuel-injection systems, MOSFETs are required to operate with a repetitive avalanche condition. Therefore, it is vital that the ruggedness of MOSFETs against repetitive avalanche is taken into consideration during the design phase of the technology, and an evaluation method can be established to rate the repetitive avalanche performance. In this paper, a system using a half bridge DC-DC buck converter, which is close to a typical real-life application in both frequency and avalanche energy, is introduced for evaluating the repetitive avalanche performance of power MOSFETs. In particular, the wear-out mechanisms due to off-state repetitive avalanche are investigated for different device technologies, giving an insight into the ruggedness of these different device technologies and their suitability to demanding applications.