High voltage generic switching transistor

[John K]

I am simulating a cirduit with a STR1550 high voltage (500V) transistor. Since the correct transistor model is not available, I used the generic model. Since I only use the transistor as a switch, I assumed this would work well. However, it turns out that the leakage current in the off-state is far too high. This causes problems when simulating the circuit.
I appreciate that all transistors types cannot be modelled. However, it would be nice if there was a generic model that covered switching transistors with a specified hFE and perhaps specified leakage current, and which could be applied for all voltages.
Any chance of having this added to the library? Or, are there any other approaches that could solve the problem?

[Ettore]

...Since the correct transistor model is not available, I used the generic model.

You won't get a reasonable result using the generic BJT model in any case; you should view at this generic model just as the elementary brick to build a wall.

...Any chance of having this added to the library? Or, are there any other approaches that could solve the problem?

Unfortunately the datasheet is not giving all details away one needs for.
A solution - although often not practicable - is to request a SPICE model to the manufacturer, who knows better than anyone his product.

Anyway, here it is attached a simulating model attempt for such an high voltage BJT.
Appreciate that SPICE3 simulates optimistically hFE above reported current rating in the datasheet. This is particularly true for high voltage BJT operating with low VCE.
In particular I did set BF (hfe)=150 and VAF=2000 in order to make hFE as constant as possible with low VCE ranges, but this is less efficient in SPICE3 compared to others evolute version as HSPICE.

About switching storage and transition times, the datasheet won't report anything useful so I set involved parameters to standard high speed values.
You may want to adjust TF and TR and junction capacitances values if needed.

[John K]

Thanks for reply!
I have tried the model. However, I get leakage current which is far too high.
In my circuit, the transistor is either fully off or fully on most of the time, so I am not really concerned about most of the transistor characteristics. All I need is a correct leakage current in the off-state and correct hFE so that I can test the rest of the circuit. I suppose I can change BF to get the correct hFE.
Is there any way I can achieve the desired leakage current? I do not have any knowledge of the model used so I do not understand what the parameters mean.
Best regards
John

[Ettore]

I get less than 2nA leakage in off condition @VBE=0. Did you change SPICE parameters in Set Animation Option ? Could you post your circuit or part of.
Yes, BF sets hFE. ISE sets leakage current.

[John K]

The transistor actually works with the desired leakage current, which I now can alter to the required value.
There was a circuit error which confused me, but the model seems to be working as it should.
Thank you for your advice!
Best regards
John K