Modifying an existing SPICE model

From LTwiki-Wiki for LTspice

I want to use a specific MOSFET for simulation, now I can't find any model for LTspice. I just found a datasheet - is there a realistic possibility to transfer the values into LTspice so that I have my own model of this MOSFET? The name of the MOSFET I want to use is Si1499DH.

.model Si1499DH VDMOS pchan + Vto=-0.85 Kp=9 Rg=9 Rd=30m Rs=12m + Cgdmax=0n5 Cgdmin=0n1 Cgs=0n5 + Cjo=80p Is=25p Rb=50m N=1.13

This is based on a starting point of the Si3445DV, which exists in LTspice, and then using the data sheet values to modify the existing model, which is about twice the die area, but is other- wise very similar. It is not tested, but is an educated guess from past experience.

As a second alternative, you could select the existing Si3445DV, which comes with LTspice, and add an "M" multiplier parameter to scale the die area by 0.5 or 0.6. Ctrl-right-mouse-button click on the MOSFET and then edit the Value2 attribute to be M=0.5.