Re: Another discrepancy (LTspice/switchcad3)

Robert,

>>> The results are way off.
>>
>> The simulation is probably right around correct.
>> That FET and diode have capacitance. .
>
> Adding a small capacitance has no effect.

But that doesn't remove the capacitance that's already
swamping the circuit. The problem is the circuit design,
not the models.

> I will try your 1619 circuit later

That one works. Notice that that SMPS topology is
a boost. To get higher output voltage, you might try
a tapped-inductor boost. That will reduce the voltage
rating required of the MOSFET and make the circuit
less sensitive to its capacitance. If you're not really
after a SMPS, but some high impedance high voltage,
you can probably get a chopped square wave working
into a diode voltage multiplier to work. That gets rid
of the problem of getting high impedance energy
storage inductors with little stray capacitance.

-Mike


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