The switching waveforms of a series of power MOSFET devices called Logic Level FETs (L2FETs) and featuring a 5V gate drive are presented and contrasted with those of the more conventional 10V gate drive devices. A new method of characterizing MOSFET switching performance is discussed in which the MOSFET is treated as a vertical JFET driven in cascade from a low voltage lateral MOS. The 2:1 advantage in rise and fall time and the 4:1 reduction in switching “dynamic V(SAT)” dissipation with constant drive power of the L2FET over the 10V MOSFET are demonstrated and discussed.–Article Quote
The topics discussed inside the application note including the background, a brief review of L2FET Characteristics compared to standard types, switching waveforms with conventional drive, switching waveforms with constant current drive, large signal equivalent circuit of the MOSFET, waveforms expected, new switching characterization for power MOSFETs, and the gate voltage propagation effects.
Gate-propagation effects may be reduced by the following design methods:
1. Many gate runners.
2. More conductive polysilicon.
3. Silicide rather than polysilicon gates.
4. Less cells (resulting in lower transconductance and higher rDS(ON)).
5. Substantially different lateral and vertical structure.
6. High-frequency packaging.
Source : Faichild Semiconductor
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