ECD 442 Power Electronics1 Power MOSFETs Two Types –Depletion Type Channel region is already diffused between the Drain and Source Deplete, or “pinch-off”

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Presentation on theme: "ECD 442 Power Electronics1 Power MOSFETs Two Types –Depletion Type Channel region is already diffused between the Drain and Source Deplete, or “pinch-off”"— Presentation transcript:

1 ECD 442 Power Electronics1 Power MOSFETs Two Types –Depletion Type Channel region is already diffused between the Drain and Source Deplete, or “pinch-off” the Channel –Enhancement Type No channel region exists between the Drain and Source “Invert” the region between the Drain and Source to induce a channel

2 ECD 442 Power Electronics2 Depletion MOSFET

3 ECD 442 Power Electronics3 N-Channel Depletion MOSFET Normally Reverse-Bias the Gate-Source Junction

4 ECD 442 Power Electronics4 Enhancement MOSFET

5 ECD 442 Power Electronics5 N-Channel Enhancement MOSFET The Gate-Source Junction will be Forward-Biased The bias voltage must be greater than a “threshold” voltage A Channel region is induced between the Drain and Source

6 ECD 442 Power Electronics6 Drain Characteristics

7 ECD 442 Power Electronics7 Steady-State Characteristics

8 ECD 442 Power Electronics8 Switching Characteristics

9 ECD 442 Power Electronics9 Equivalent Circuit

10 ECD 442 Power Electronics10 Switching Model

11 ECD 442 Power Electronics11 Switching Waveforms and Times

12 ECD 442 Power Electronics12 Turn-on Delay, t d(on) = time to charge the input capacitance to V T Rise time, t r = Charging time to charge the input capacitance to the full gate voltage, V GSP in order to drive the transistor into the linear region of operation

13 ECD 442 Power Electronics13 Turn-off delay time, t d(off) = time for the input capacitance to discharge from “overdrive” voltage V 1 to pinch-off. V GS must decrease significantly for V DS to rise. Fall time, t f = time for the input capacitance to discharge from pinch-off to the threshold voltage.


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