Model with subckt dependancies not simulating

[Shawn_1998]

Hello All,
I am trying to simulate the LM4871, class-AB audio amplifier as a replacement for the LM9022 filament driver for vacuum fluorescent displays. I have constructed the circuit according to the typical application suggested in the datasheet.

However, I am not seeing the output I would expect. I expect to see sinusoid output for a SINE input.

I assume the issue is with the LM4871 PSPICE model I got from Texas Instruments. I took the “lm4871.lib” from the model file. I dropped it into the schematic and auto-generated a symbol. This file has several SUBCKT dependencies within it, so I did a “.inc lm4871.lib”.

Any advice on what to do would be appreciated as I am still learning my way around QSPICE.

[KSKelvin]

Replicate exact circuit from Pspice. It is interesting that the feedback in Pspice example (also TI-TINA example) is into +IN but datasheet example is into -IN. TI made a mistake either in datasheet or its simulation file?

By the way, Qspice can accept auto symbol generation with a file consist of many .subckt, you just have to select “Include Entire File” in Autogenerate Symbol window.

Parent.LM4871.qsch (9.5 KB)

TI LM4871 datasheet