I'm behaviorally modeling a _system_ that includes the discrete device Supertex VP2450.
At the Supertex/Microchip site, it says no Spice model available :-)
Does anyone know of a model?
Thanks! ...Jim Thompson
I'm behaviorally modeling a _system_ that includes the discrete device Supertex VP2450.
At the Supertex/Microchip site, it says no Spice model available :-)
Does anyone know of a model?
Thanks! ...Jim Thompson
-- | James E.Thompson | mens | | Analog Innovations | et |
Why not just use some similar part that you have a model for? That mosfet is not at all unusual, and they are not precision parts anyhow.
That's what I usually do for vanilla diodes, transistors, or mosfets: pick something close that LT Spice already has. Exotica, like phemts or depletion fets or jfets, justify more exact models.
Or, if you really want a VP2450 model, pick a similar mosfet model and tweak the params.
-- John Larkin Highland Technology Inc www.highlandtechnology.com jlarkin at highlandtechnology dot com
500V PMOS
The problem is nailing the GBW product of this monster. ...Jim Thompson
-- | James E.Thompson | mens | | Analog Innovations | et |
Spice models of semiconductors rarely include breakdown voltage. LT Spice is happy to run a 1N4148 at -100 kilovolts.
That part is not avalanche rated, so don't let the drain voltage hit -500.
As I said, pick something close. The GBW won't be precise anyhow. Your circuit should have a lot of tolerance for fet capacitances and such.
Hey, you are supposed to be the model creation guru, so create a model.
-- John Larkin Highland Technology Inc www.highlandtechnology.com jlarkin at highlandtechnology dot com
Takes data to make a model. That is lacking, and the customers measurements are suspect. ...Jim Thompson
-- | James E.Thompson | mens | | Analog Innovations | et |
I suppose one could insert the "BV" parameter in a existing model, that is, if the model being used has that.
If you use a VDMOS, you can apply the BV Vds(Break down voltage) Oh well.
Jamie
I'm behaviorally modeling a _system_ that includes the discrete device Supertex VP2450.
At the Supertex/Microchip site, it says no Spice model available
Does anyone know of a model?
Thanks! ...Jim Thompson
I haven't found many of Supertex's models to converge well, or even seem to replicate the part very well. Sometime they'd supply something with text that 'looked' like a .cir file, Had to check all the default prarameters and then 'correct' the forms, but that was a few years ago.
Do you have this one? the VN2450.
*
I didn't see it anywhere in the 35MB of Alex Bordodunov's models, but he might have one. Did you email him?
I am no model expert, let alone understanding some of the spice parameters that are not even seen in the data base models, but I came up with this using supertex PDF file, as vague as it was. Lots of items not specified in it and some that are, I don't see where to apply them in spice, because like I said, I ain't no model expert.
I ran this using their test jig and the charts to do some compares.
.model VP2450 VDMOS(pchan Rg= 3 Rd=15 Rs=15 Vto=-2.0 BV=-500 Kp=320 Cgs=190p Is=1e-30 CgdMax= 75p)
There are items missing for the body diode for capacitance etc..
Then I apply it in an inductive test app and seems to look ok.
Oh well.
Jamie
Jamie
.model VP2450 VDMOS(pchan Rg= 3 Rd=15 Rs=15 Vto=-2.0 BV=-500 Kp=320 Cgs=190p Is=1e-30 CgdMax= 75p)
Ahmm.... Is is a tad small, and may cause convergence problems. A 1uX1u diode junction will be of the order of < 1e-18, usually
Bigger discrete devices might be hitting 1e-15, or thereabouts
Kevin Aylward B.Sc.
A published model I found had AD, AS=1. Scratched butt, guesstimated
1u, it then simulated OK. ...Jim Thompson-- | James E.Thompson | mens | | Analog Innovations | et |
True, but like I said, I am not an expert at this but, the PDF for the component claims a -1.8V forward drop on the body diode, if you can believe that, unless I misunderstood something..
So at 100mA 1e-30 31 was hitting close to home after running some sims and comparing values.
Maybe some one else can get it closer..
Jamie
Hmm. Silicon is silicon. It's still going to turn on around 0.6V -- it would be amazing physics otherwise. That would suggest ESR around
1.2V/100mA = 12 ohms max. I forget if the MOS model includes RD/RS parameters, but these can be added externally if not. IS can then be specified based on leakage and lower current behavior (it should be fairly "ideal diode" under 10mA).Not much to say about one datapoint unfortunately. And it's a maximum, not typical, and certainly not plotted. How lazy. Probably a good idea measuring a few.
Tim
-- Seven Transistor Labs Electrical Engineering Consultation
They possibly made the 101 error of not setting N in exp(Vbe/Vt.N) to its correct value, from its default of 1, or possibly they set the diode resistance incorrectly.
For example, to model LEDs, N might be 2.5. to get the several volts that it has.
"Is" is the reverse leakage current of a diode. No way is it 1e-30 amps!
Kevin Aylward B.Sc.
Ok.
.model VP2450 VDMOS(pchan Rg= 3 Rd=5 Rs=9 Vto=-2.0 BV=-500 N=2.3 Kp=
320 Cgs=195p CgdMax=75p)I think there as a reason where there is no model out there for this.
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