TINA/Spice/LM5116: Unencrypted PSPICE model for LM5116 simulation

Kpk,

Which model did you download to use? The Average model would not have any switching and would only contain the information for the AC simulation of the Bode Plot.

The transient model imports correctly and works correctly in TINA-TI

Is it possible that your SS cap is too large for your simulation time chosen? You should still see switching after a few ms of simulation. We reduce it to 5nF so the simulation will only take 6ms for the reference design (it is 100n in the actual design).

Here is the circuit that was used:

Did you try to export the circuit from WEBENCH for Altium? You could create a design close to your requirements and export it from WEBENCH for use in Altium. This would eliminate any issues during import.

Hi Britt,

We did try the following several approaches:

1. Download the AC transient model and bind to Altium schematic drawing, but there are several errors. What I can remember the most clear is a MOSFET model which was marked as Level 8 but should be Level 7 or something. And there are several VSWITCH model incompatible. After changing all these, it's quite same with TINA-TI's internal SPICE model.

2. Export from Webench into Altium format directly for 85V DC IN, 80V 3A DC out with all default settings, the simulation still cannot converge.

3. Copy from TINA-TI's SPICE model of LM5116, into #1's schematic. The simulation can converge but there's no output. We saw that SS/SYNC signal is not ~1V like in TINA-TI and found that the internal clk signal seems not to be oscillating for LM5116. We suspect such is the reason.

4. We went back to TINA-TI. As our design requirement is 85V~95V DC IN and 36~80V DC out with ~8Ohm resistance load, we started from 80V out but when we tune down the output voltage, we could not find a general parameter set which would work throughout the output range. BTW we were not asking Webench for 80V 10A as it would only allow me to put 80V 3A. So we put parallelly 3 set of output MOSFET bridges. And TINA-TI kept saying unable to converge although sometimes I put in the suggested value by Excel spreadsheet. And, currently, I'm confused by the parameter sets. There is a bit difference between parameters given by Webench and the Excel sheet. I know there is different optimizing concerns, but which one would you suggest to be the start of design? Thanks so much.