SLVAFF0 September   2022 TPS25947 , TPS2597 , TPS25981 , TPS25982 , TPS25985


  1.   Abstract
  2.   Trademarks
  3. 1Understanding the FET SOA
  4. 2Ensuring FET SOA in Hot-Swap Design
  5. 3eFuse Ensuring Integrated FET SOA Operation
    1. 3.1 Thermal Shutdown
    2. 3.2 eFuse Response to Events Stressing Integrated FET
  6. 4Plotting eFuse AOA
  7. 5eFuse Application Design Recommendations to Ensure Integrated FET Reliability
  8. 6Summary
  9. 7References


Applications such as Hot-swap where Power FET is operated in saturation region under high stress, FET safe operating area (SOA) is a major concern for system designers. Designers need to study the FET SOA curve available in the manufacturers data sheet and determine if the FET can handle the power stress without undergoing damage. This application report covers the significance of FET SOA, how the manufacturers derive SOA plot, and how the hot-swaps designers make sure that external FET is operated within specified SOA. Then, the eFuse protection schemes which help to ensure SOA of the integrated FET are discussed and a detailed method of deriving AOA (Allowed Operating Area) plot from the eFuse data sheet is presented. Finally, design recommendations are shared to prevent violation of eFuse abs maximum rating, and to provide long term reliability of eFuse.