A Split-Gate Power MOSFET Obtaining Ultra-Wide SOA Based on Time-Shared and Partitioned Conduction Gate Control

Power MOSFETs are typically used as switches in the soft-start circuit of hot-swap systems, especially the split-gate trench MOSFETs (SGT-MOS) which has ultralow ON-state resistance ( ${R}_{\mathrm{\scriptscriptstyle ON}}$ ). Whereas the safe operating area (SOA) of SGT-MOS collapses as power density increases. So far, the investigation to balance the ${R}_{\mathrm{\scriptscriptstyle ON}}$ and SOA of the SGT-MOS mainly focuses on the improvement of the device structure and packaging. The problem is not yet fundamentally solved. In this article, the collapse of the SOA of power MOSFETs under linear mode operation has been minutely studied. The mechanism of thermal runaway and the effect of the $ {R}_{\mathrm{\scriptscriptstyle ON}}$ of MOSFET on its SOA have been revealed as well. It is noted that the degradation of the linear mode operating capacity of power MOSFETs is the root cause for the narrowing of the SOA, which is reflected in the shrinkage of the power dissipation limit. The analytical model of local temperature rises and device temperature coefficient (TC) is established. Reducing the current TC of the power MOSFETs is the key to improve the thermal stability and to broaden the SOA. On the basis of researched results, an intelligent power MOSFET architecture with ultra-wide SOA is proposed. The innovative power device surmounts the trade-off between the SOA and ${R}_{\mathrm{\scriptscriptstyle ON}}$ . As a result, the linear capacity of the power MOSFET proposed is high enough to compare that of the latest commercial linear MOSFET product from Infineon.