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bare bones charge pump

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Ian.M:
There's little dispute that LTspice has one of the best SPICE engines and most comprehensive component libraries* of all freeware or non-crippled free demo PC SPICE packages.  Its UI is somewhat clunky but is consistently usable. Where you'll find it lacking when compare to payware SPICE programs is presentation of results. e.g. It lacks pretty on-schematic 'meters' - you have to open the error log to see .measure results or click a trace in the waveform viewer to put a cursor readout on it. 

Although its developed primarily to run on Windows, its development team actively check for WINE compatibility, so you shouldn't have much trouble getting it running on any 'mainstream' x86 LINUX distro.

Unfortunately LTspice doesn't support the package/footprint and part number attributes for each component that are essential for PCB layout, nor does it have explicit support for multiple devices in a single package, nor for tagging some parts as for sim only, so its a very poor schematic editor for PCB layout.  If your layout package can import from LTspice, you'll need to do a lot of fixup work to assign footprints and part numbers.  Going the other way, exporting a schematic from a layout package to LTspice for simulation is much easier if your layout package supports it or has a full scripting language that can write arbitrary files.  If not, you can almost certainly export a simulatable netlist that LTspice will accept, though that looses you point and click waveform probing.

* If you include user contributed libraries from ltwiki.org and the LTspice Yahoo group.

MagicSmoker:

--- Quote from: OM222O on July 15, 2019, 12:25:55 pm ---...
after the LTspice crashed, I went back and this time increased the base resistor values and dropped the capacitor values, added a second inverting stage and a few other minor tweaks and this time it works fine.
...
I'm also going to attach the .asc file for the two stage inverting simulation. feel free to play around with it.

--- End quote ---

Your circuit is a little clunky but it simulates fine for me, even with that brutal 100mA constant current load on the output of the charge pump multipliers. That said, I do use the alternate solver and set trol to 4 instead of the default of 1.

And I agree with Ian.M that LTSpice has an excellent SPICE engine. In fact, it was what changed my mind completely about SPICE, which I had written off as totally useless (especially for SMPS design, which is what I mostly do).

Ian.M:
Hmmm.  I've been playing with a sim of a brute of a voltage doubling charge pump.  It delivers -20V into 50 ohms, which is 400mA, with nearly 75% efficiency and runs at approx 950KHz to do so with relatively small capacitors.  It has a single BJT Colpitts oscillator (I assume you can scrounge up a small plain inductor) driving a BJT push-pull emitter follower buffer driving complimentary power MOSFETs.  I'm sure it needs a lot more work before a real-world implementation will keep the smoke in. I'd be especially wary of the pump's flying capacitors: 1.7A RMS is a bit much for most 330nF caps!

ledtester:

--- Quote from: Ian.M on July 18, 2019, 12:02:30 pm ---... Unfortunately LTspice doesn't support the package/footprint and part number attributes for each component that are essential for PCB layout, ...

--- End quote ---

At one point Eagle tried to support import/export to and from LTSpice. However, they've abandoned that in favor of building simulation into Eagle using the open source ngspice.

KiCad also supports simulation, and you can use LTSpice as the simulation engine.

However, it seems that the trend is to layout the circuit and initiate simulation from your PCB design application.

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