Experimental Validation of Triangular SOA via Infrared Thermography of a MOSFET Die Operating in the Thermally Unstable Linear-mode for Automotive Applications

This paper explores for the first time the robustness of triangular and rectangular pulses of equal energy through thermal analysis, looking at hotspot formation across the die of a power MOSFET during operation in its electro-thermally unstable linear-mode region. This research demonstrates the validity of a technique widely employed for thermally stable linear-mode operation, considering three types of power pulses corresponding to different automotive applications: i) rectangular ii) triangular - linearly decreasing current with constant voltage and iii) triangular - linearly decreasing voltage and constant current. In automotive applications, these types of triangular pulses are characteristics of active clamp and capacitive pre-charge, respectively. In this work, we use an exposed low voltage power MOSFET and present experimental data to prove the 2x SOA capability for triangular pulses uniquely from a thermal point of view. In contrast to our previous work, the same device under test (DUT) will be subjected to three different operating conditions and imaged using infrared thermography, thus avoiding the destruction of the sample for the validation of the technique.