internal nodes GRRRRR...

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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.





--

Anybody can count to one.

- Robert Widlar
 
jlarkin@highlandsniptechnology.com wrote:
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.
Click to expand...

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.
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.
Click to expand...

Or a 1-ps transmission line--duelling bugs!

Cheers

Phil Hobbs


--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com
 
On Sat, 28 May 2022 18:25:49 -0400, Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:

jlarkin@highlandsniptechnology.com wrote:
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.

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.

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.

Or a 1-ps transmission line--duelling bugs!

Cheers

Phil Hobbs
Click to expand...

That\'s a neat idea. A txline is a DC-coupled 1:1 transformer.



--

Anybody can count to one.

- Robert Widlar
 
On Sat, 28 May 2022 09:32:41 -0700, jlarkin@highlandsniptechnology.com
wrote:

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.
Click to expand...

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 LTspice@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
 
On Sun, 29 May 2022 13:22:54 -0400, legg <legg@nospam.magma.ca> wrote:

On Sat, 28 May 2022 09:32:41 -0700, jlarkin@highlandsniptechnology.com
wrote:

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.

Assuming that\'s really the problem:
Click to expand...

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.

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.
Click to expand...

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.


I\'d consult LTspice@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
Click to expand...

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.



--

Anybody can count to one.

- Robert Widlar
 
legg wrote:
On Sat, 28 May 2022 09:32:41 -0700,
jlarkin@highlandsniptechnology.com wrote:

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.

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 LTspice@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.
Click to expand...

Plus their part selector is horrible--there\'s no way to search on
parameters, or even device type.

Cheers

Phil Hobbs


--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com
 
On Sat, 28 May 2022 16:20:48 -0700, jlarkin@highlandsniptechnology.com
wrote:

On Sat, 28 May 2022 18:25:49 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

jlarkin@highlandsniptechnology.com wrote:
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.

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.

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.

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.
Click to expand...

You\'ll have the same issues placing digital logic on flying
nodes.

RL
 
legg wrote:
On Sat, 28 May 2022 16:20:48 -0700, jlarkin@highlandsniptechnology.com
wrote:

On Sat, 28 May 2022 18:25:49 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

jlarkin@highlandsniptechnology.com wrote:
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.

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.

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.

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.

You\'ll have the same issues placing digital logic on flying
nodes.

RL
Click to expand...

More tlines!

Cheers

Phil \"Everything\'s a transmission line anyway\" Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com
 
On Sun, 29 May 2022 16:22:53 -0400, legg <legg@nospam.magma.ca> wrote:

On Sat, 28 May 2022 16:20:48 -0700, jlarkin@highlandsniptechnology.com
wrote:

On Sat, 28 May 2022 18:25:49 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

jlarkin@highlandsniptechnology.com wrote:
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.

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.

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.

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.

You\'ll have the same issues placing digital logic on flying
nodes.

RL
Click to expand...

Yes. They are ground referenced for sure.

--

John Larkin Highland Technology, Inc trk

The cork popped merrily, and Lord Peter rose to his feet.
\"Bunter\", he said, \"I give you a toast. The triumph of Instinct over Reason\"
 
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