Hello,
I am trying to both learn LTSpice and analyze a circuit that I have designed. However, I haven’t been able to get the expected results from my simulation. I have attached my design file. Could you please help me with this?

 

Hi Bora,
Please post your UC28 model and asy file
E

 

Hi Bora,
Please post your UC28 model and asy file
E

Hi Bora,
Please post your UC28 model and asy file
E

files of the parts I added as extras.

Thanks.

 

Hi Bora,
Got the extra downloads OK.
The circuit has a lot of error messages, what is the problem you are seeing on the simulation.

E

 

Frankly, I don't know much about LTSpice. I'm trying to learn, and since I'm not very familiar with the program and testing my circuit, I can't see my mistakes. It's very difficult to find resources to learn this application in my country.

Hi Bora,
Got the extra downloads OK.
The circuit has a lot of error messages, what is the problem you are seeing on the simulation.

E

 

Hi Bora,
Can you post a rough description of what you expect the circuit to do?

You have chosen a very difficult circuit to start learning LTSpice.
E

 

Hi Bora,
Can you post a rough description of what you expect the circuit to do?

You have chosen a very difficult circuit to start learning LTSpice.
E

I'm trying to test the compensation portion of the SMS flyback design and its effect on the circuit. I'd like to see if I should use single compensation on the TL431 and UC3842 sides, or if this approach would yield cleaner results.

 

hi Bora.

The full circuit is too complex to run with all the errors.
One method to debug, is to breakdown the full circuit into working sections.

This plot and circuit show an edited output stage, the modifications are to enable the circuit to simulate, it needs some redesign.

I suggest you debug the full circuit using an asc file for each section and then debug the remaining circuit sections using their own asc file.

E

 

hi Bora.

The full circuit is too complex to run with all the errors.
One method to debug, is to breakdown the full circuit into working sections.

This plot and circuit show an edited output stage, the modifications are to enable the circuit to simulate, it needs some redesign.

I suggest you debug the full circuit using an asc file for each section and then debug the remaining circuit sections using their own asc file.

E
View attachment 355446

Thank you very much for your effort..

 

I don't trust some of the SPICE models on the internet. Try the LT1243, LT1242 parts. They are a little different, but I know they work with LTspice.

The clamp diode should be much faster than the 1N4007.