MCP6N11
500 kHz, 800 µA Instrumentation Amplifier

When I simulate it, i get this error. Please help. I have attached the lib file. Thanks

 

The fault may not lie with the amp model itself. It's a common error message. Try adding a few parasitic values to components in your schematic., e.g. give any voltage source or inductor some small but finite internal series resistance.

 

Hi,

Here is my schematic. Could you please tell where to add parasitics?



Thanks

 

Try right-clicking V1 and/or V2 and setting its series resistance parameter to 1 Ohm. Adding a decoupling cap of 1uF across V1 and/or V2 might also help.

 

Thanks for helping me. I still see the same problem.

 

So it seems the problem could well be within the IC model.
Does putting some small resistance between Vref and Vss make any difference?
You could also try editing the simulation command by checking "Skip initial operating point solution".

 

I tried adding these. It didn't help

 

Hi j123,
Please post your latest asc file and the 6N11 model.
E

 

Hi,

Here are asc file and MCP6N11 model file.

Thanks

 

Hi j123,
Sorry to be a pain, but please post your 6N11 asy file.
E

Update, created the asy file from the text file.
I get the same error as you, perhaps @Bordodynov could advise.

E

 

Have you tried using this options?
.opt cshunt=10f gshunt=1n

 

Hi Jony,
Tried adding those options, it runs, but very slow, also reports a number of errors.
E

 

@ericgibbs Thank you very much for trying it in LTspice!
@Bordodynov Could you please help me in fixing these LTspice errors?

 

Show the log file. Hit ctrl L to get an error log file.

 

Hi @Lightium,

This is the error log file.

Fatal Error: Analysis: Time step too small; initial timepoint: trouble with node "u1:_u3:37a"



Thanks

 

Where is the symbol file for the MCPN11?

 

Hi L,
Try my asy file.
E

 

I get trouble with node " u1:_u3:50 ". I'll look into this, but it's late.

 

Well, for starters R94 and R97 can't be zero. So I will change their values to 0.2 for now, again it's late for me. See you later.

 

I've just noticed your model seems to be for the 'Minimum Gain = 5' version of the chip, but you have set the gain = 2 via R93,R96. Could that be an issue?