LT Spice ideal diode

Perfect diode...

Though I'd think one could conjure up a behavioral rendition. I'll think on it ;-)

Make your own zener...

• IS = {IS}
• RS = {RS}
• N = 1
• EG = 1.11
• BV = {BV}
• IBV = {IBV}
• CJO = {CJO}
• VJ = 0.75
• M = 0.33 ) .ENDS MyZENER

I have a configurable symbol in my symbol library. ...Jim Thompson

Sure there is, just open "CompliantParts.SLB" on the Subcircuits and Symbols page of my website (it's plain text).

A current source with no reverse current and a finite curvature can be thought of as the same as a (nearly) ideal diode.

It's TANH, so all derivatives are there and smooth, so it converges nicely.

Just set a transition region and a max current to suit.

I'll generate something more understandable by Larkin when I have a free moment :-)

Maybe a symbol with parameters to make it easy :-) ...Jim Thompson

"John Larkin" wrote in message news: snipped-for-privacy@4ax.com...

You can add Capacitors to the database, but they left out the interface to add a diode. I think you can go into C:\Program Files\LTC\LTspiceIV\lib\cmp\standard.dio and just add your own. It might choke on multi-line model.

Cheers

Never mind, I figured out the ideal diode.

Click the D thing and add a diode to the schematic. Rename it Didl.

Then add a spice directive string nearby...

.model Didl D(Ron=0.1 Roff=1G Vfwd=0)

with whatever values you think are close to ideal. For some reason, my sim slows down if I use too low an Ron value. The 0.1 is good enough.

The ideal zener is then just a voltage in series with this diode.

I'm doing what the controls guys call a "high select", to create a voltage that's the greater of two inputs, to switch my power supply from constant-current to constant-voltage mode. I did a clever thing with two switch elements, but it did funny things sometimes and was too hard to think about.

John

Maybe not even that complex. Maybe just write your own diode equation? ...Jim Thompson

"John Larkin" wrote in message news: snipped-for-privacy@4ax.com...

Someone has a patent on I think its on the fly C-mode to V-mode switching, you might want to look that up. Hint, they are on LI NY.

Cheers

Power supplies with separate voltage and current set pots have been around for 50 years or so, so there's nothing fundamental about this. Are there still any power supply companies on LI?

About LT Spice: where the heck is the "draw" menu? And why does it keep moving my schematic around in the view window, jamming it against the left and right edges at random?

John

Hello John,

This "draw" menu is in Edit->Draw

You can switch off the automatic scroll-view in the Control Panel -> Drafting Options

Best regards, Helmut

Ah, cleverly hidden. Thanks.

John

Ok, now that you have the ideal diode, a zener can also be sim'd by a voltage source and one of your ideal diodes in series with it. Plus a non-ideal one across if your zener needs to also be used in reverse. The voltage source lets you dial in the zenering voltage. There's probably an easier way but I've done it a few times where that was good enough.

I did not check out your solution yet. I take N=0.001 in the diode equation to approximate the ideal one.

.model Didl D ( N=0.001)

Pere