Some LT Spice models have invisible internal nodes that are hard ground. So you can't float them off ground.
LTC4444 mosfet driver for example, half-bridge with + and - power rails. Bummer.
I'll just fake the gate driver with a couple of BVs. That will run faster anyhow.
I guess I could run the 4444 grounded and AC couple into the gates with DC restore. Lotta hassle.
Haven't run into that one for a built-in LTspice model. Maybe it's one of the post-Engelhardt ones.
Do they have a PSPICE model? If so, it could maybe be fixed with a search+replace.
Or a 1-ps transmission line--duelling bugs!
Cheers
Phil Hobbs
That's a neat idea. A txline is a DC-coupled 1:1 transformer.
Assuming that's really the problem:
You can create a node that serves as YOUR ground. Call in GND or whatever. If there are 2xmodels with internal common nodes, I don't think you can isolate between them.
I'd consult snipped-for-privacy@groups.io .
I generally don't use their models, unless they serve as equivalents to more generic devices or do somethging unique that justifies cost of real part use.
RL
Maybe not. I can apply 100 volts to all pins of the LTC4444 and no current flows.
There must be some other reason it won't swing to a V- rail.
I'm making a floating 3-phase AC power supply, with three half-bridges switching between +60 and -60. I have a floating common called N, namely the neutral of a 3-phase wye system. It's another PM alternator simulator.
It's a nuisance to simulate. And very slow.
Something exotic like this mosfet driver is worth simulating with a good model. And it's worth paying more for a part with a good model, which is I guess the point of free LT Spice.
Plus their part selector is horrible--there's no way to search on parameters, or even device type.
Cheers
Phil Hobbs
You'll have the same issues placing digital logic on flying nodes.
RL
More tlines!
Cheers
Phil "Everything's a transmission line anyway" Hobbs
Yes. They are ground referenced for sure.
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