Introduction to MOSFET
Introduction to MOSFET:
Fig: Varieties of symbols used for MOSFETS
- The Power MOSFET technology has mostly reached maturity and is the most popular device for SMPS, lighting ballast type of application where high switching frequencies are desired but operating voltages are low.
- Being a voltage fed, majority carrier device (resistive behavior) with a typically rectangular Safe Operating Area, it can be conveniently utilized. Utilizing shared manufacturing processes, comparative costs of MOSFETs are attractive.
- For low frequency applications, where the currents drawn by the equivalent capacitances across its terminals are small, it can also be driven directly by integrated circuits. These capacitances are the main hindrance to operating the MOSFETS at speeds of several MHz.
- The resistive characteristics of its main terminals permit easy paralleling externally also. At high current low voltage applications the MOSFET offers best conduction voltage specifications as the RDS(ON) specification is current rating dependent.
- However, the inferior features of the inherent anti-parallel diode and its higher conduction losses at power frequencies and voltage levels restrict its wider application.