3-15. Performance of MOSFETs: Safe Operating Area(or Area of Safe Operation)

There are two modes of safe operating area (SOA).

(1) Forward Bias SOA (F.B. SOA): Usable area of current and voltage at ON status.
(2) Reverse Bias SOA (R.B. SOA): Usable area of current and voltage at turn-off operation.

Applied pulse width is very narrow because of use under switching operation.

Each mode can be defined as shown in Fig. 3-12(a).

Defining SOA in actual operation
Fig. 3-12(a) Defining SOA in actual operation
Example of MOSFET’s F.B.SOA
Fig. 3-12(b) Example of MOSFET’s F.B.SOA
  • As for the guarantee of avalanche, rated voltage / current operation (short time) at turn-off is generally guaranteed as for the MOSFET, but R. B. SOA has not been announced.
  • F.B.SOA consists of three restriction areas, rated current, rated voltage and thermal resistance areas, and secondary breakdown area.
  • The three restriction areas are limited by ratings of device or calculated from thermal resistance. But secondary breakdown area is obtained by measurement of the actual device.

Chapter III : Transistors

3-1. Types of Transistors
3-2. Bipolar Transistors (BJTs)
3-3. Bias Resistor Built-in Transistors (BRTs)
3-4. Junction Field-Effect Transistors (JFETs)
3-5. Metal-Oxide-Semiconductor Field-Effect Transistors (MOSFETs)
3-6. Differences between BJT and MOSFET
3-7. Structure and Operation of MOSFET
3-8. MOSFET Performance Improvement: Decision Factors of RDS(ON)
3-9. MOSFET Performance Improvement: Approach to Low RDS(ON)
3-10. MOSFET Performance Improvement: Super-Junction MOSFETs (SJ-MOS)
3-11. Summary of MOSFET Features by Structure
3-12. Performance of MOSFETs: Drain Current and Power Dissipation
3-13. Performance of MOSFETs: Avalanche Capability
3-14. Performance of MOSFETs: Characteristic of Capacitance
3-16. Insulated-Gate Bipolar Transistors (IGBTs)
3-17. Operation of Insulated-Gate Bipolar Transistors (IGBTs)
3-18. Performance Improvement of IGBTs: Evolution of Vertical Design
3-19. What are RC-IGBTs and IEGTs?
3-20. Application of IGBTs
3-21. Comparison of Forward Characteristics of IGBTs and MOSFETs
3-22. Comparison of Transistors by Structure
3-23. Datasheets of MOSFET: Maximum Ratings
3-24. Datasheets of MOSFET: Electrical Characteristics
3-25. Datasheets of MOSFET: Capacitance and Switching Characteristics
3-26. Datasheets of MOSFET: Body Diode

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