Anyone have experience with SPICE models of BSS84 especially those usable with LTspice?
The NXP model in the LTspice library seems closest to DS (datasheet) for Vds - Id but is still far out circa Vgs 2.5V
There's a Diode International model but that is WAY out for all Vds - Id
Da TINA people like a Zetex .subckt but I haven't been able to get it to work in LTspice. Anyone know what I'm doing wrong?
I'm new to LTspice .. especially when creating 'new' components.
The NXP model in the LTspice library seems closest to DS (datasheet) for Vds - Id but is still far out circa Vgs 2.5V
There's a Diode International model but that is WAY out for all Vds - Id
Da TINA people like a Zetex .subckt but I haven't been able to get it to work in LTspice. Anyone know what I'm doing wrong?
I'm new to LTspice .. especially when creating 'new' components.
See:
.model BSS84 VDMOS(pchan Rg=3 Vto=-2.1 Rd=2.4 Rs=1.8 Rb=3 Kp=.2 Cgdmax=.04n Cgdmin=.001n Cgs=.02n Cjo=.01n Is=2p ksubthres=.1 mfg=NXP Vds=-50 Ron=6000m Qg=1n)
.model BSS84 VDMOS(pchan Rg=3 Vto=-2.1 Rd=2.4 Rs=1.8 Rb=3 Kp=.2 Cgdmax=.04n Cgdmin=.001n Cgs=.02n Cjo=.01n Is=2p ksubthres=.1 mfg=NXP Vds=-50 Ron=6000m Qg=1n)
Thanks bordodynov. But that's just the NXP model in the LTspice library. It's the 'best' I've found so far but its wonky near Vgs = 2.5V
I'm hoping someone has tried one of the published models and found it it close to the Datasheet(s).
I'm hoping someone has tried one of the published models and found it it close to the Datasheet(s).
The fact that every model has chosen to use the VDMOS model equations, may suggest that BSS84's principal application is switching circuits rather than linear circuits. Additionally the omission of a value for LAMBDA (dIDS/dVDS) , suggests that small signal behavior is unimportant (to model fitters) for BSS84.
Thanks for this bordodynov.
Your BSS84Z is the Zetex model I've been trying to get to work as a new component in LTspice without much success
. It appears closest to the datasheet(s) if we just double all the currents.Is BSS84/INF .subckt from Infineon?
Where is your BSS84p .subckt from?
Yes. It's main use is as a switcher.
How do you use LAMBDA to tweak small signal behaviour?
I'm new to dis SPICE sh*t .. especially fitting models & making new components with .subckt
Are there links to HOW TO pages in words of one syllable?
Nope, MOSFET modeling is sort of grad-school level math, and I don't know of any one syllable explanations that are both useful and correct. Here's the textbook we used at my grad school, and here's the reference book we used at the engineering company where I worked later.
What you CAN do however, is monkey around with member @bordodynov 's set of model parameters and manually add a character string like
LAMBDA={kgrlee_param}
to his .MODEL line. This tells LTSPICE that the value of the MOSFET parameter LAMBDA is equal to a knob you control, named kgrlee_param. With this in place you can have LTSPICE perform a parameter stepping test like
.STEP DEC PARAM kgrlee_param 0.0001 100 3
to sweep LAMBDA from 0.0001 to 100 with three points per decade. Then just have LTSPICE plot Ids versus Vds and observe what LAMBDA seems to do. It's fun!
What you CAN do however, is monkey around with member @bordodynov 's set of model parameters and manually add a character string like
LAMBDA={kgrlee_param}
to his .MODEL line. This tells LTSPICE that the value of the MOSFET parameter LAMBDA is equal to a knob you control, named kgrlee_param. With this in place you can have LTSPICE perform a parameter stepping test like
.STEP DEC PARAM kgrlee_param 0.0001 100 3
to sweep LAMBDA from 0.0001 to 100 with three points per decade. Then just have LTSPICE plot Ids versus Vds and observe what LAMBDA seems to do. It's fun!
Thanks for this Mark.
I'm already doing my own naively crude investigation along these lines. But it's good to know what each parameter sorta does.
I'm cleaning up a couple of domestic disasters and there's a cyclone on the way but I'll certainly have a go when/if I don't get washed away 😊
