开云体育

So I was right about two different data sources, but both are models, not one model and one measurement results.? The moral of that is, says the Duchess (not of Sussex), is 'Caveat Simulator'.

On Tue, Mar 11, 2025 at 09:52 AM, John Woodgate wrote:

It's quite possible that the data sheet Figure 13 isn't based on the Spice model, but on measurements of actual devices? of superior, rather than average, performance.

That is possible, but I think not likely.? By my read, the whole purpose of that Application Note is to show you the results of SPICE simulations.? Therefore, I think none of its plots were from measurements.? Also, it states that "the characteristics are always typical values and do not represent the limits of process variation."? I think it suggests that everything in that AppNote is average, not superior performance.

?

I agree with MaticH that the comparison is rather poor.? It should be much better, if not exact.

?

But read on.? I think there are reasons to explain it.

?

AppNote AN90034 was published in April 2022.? The LTspice model used today is dated June or July 2023.? We know it is a different model file because it lists a different number of MOSFETs than the ones shown in Figure 1 of the AppNote.

?

AN90034 refers specifically to the LTspice model here:

? ?

But the one in MaticH's (and my) simulations is here:

? ?

?

I think there was a significant change when they went from V1.1 to V3, even though it was only one year.

?

The older ZIP file is no longer there.??I tried retrieving it from the Wayback Machine but they did not successfully save it.

?

So anyway, that is what I think happened.? Nexperia's model changed significantly between 2022 and 2023 and this explains why today's simulations differ so much from the plots in AN90034.

?

To make things even more interesting, Nexperia has yet another SPICE model for the same part, here:

That one is a non-encrypted generic SPICE model (Level=3 NMOS) and it should work in LTspice as well as most other SPICE programs.? It lacks the two thermal pins.? I did not try it, but I do not expect close agreement between that model, and the AppNote.

?

Andy

?