LM27762: Using SPICE model

I was able to obtain access to PSpice for TI, and built the same schematic using the built-in available model for LM27762. Unfortunately, simulation still fails, as voltage levels do not converge:

Any help is appreciated.

Hi Luiz,

I will test the pspice model and update you tomorrow.

Thanks for your understanding.

Regards,

Febin

Hello Febin,

Thank you, I'll be waiting for any update from you.

Kind regards,

Hi Luiz,

I tried to simulate the pspice model of LM27762 and the model is working fine. Pease confirm that you are using the latest Pspice tool from TI and you are using the correct pspice model from TI product page.

Regards,

Febin

Hello Febin,

I am using the free tool "PSpice for TI", not the general-purpose PSpice. Also, I used the LM27762 model that was already available in the software, not the one downloaded from the product page. I'll try to update it.

Edit: could you show the schematic for the simulation?

Thank you for your time.

Kind regards,

Luiz Guilherme Enger

Hi Luiz,

Please try the same schematic and model from the LM27762 product page.

https://www.ti.com/product/LM27762#design-tools-simulation

Regards,

Febin

Hello Febin,

I compared the two files and the .lib are identical. Could you provide which values for capacitors and resistors you used in your simulation, so I can try to obtain the same result? Or just an image of the complete schematic.

Edit: also, the "Generate part" Tools option in PSpice for TI is not available, it remains grayed out...

Thank you.

Using MicroCap 12, the simulation tool gave a warning about some extra parameter TC for some capacitors inside the .subckt statement of the spice model for LM27762.

After removing "TC=0,0"  when it was present at the end of the line for few capacitors, I was able to run a transient simulation and obtain the +2.5 V and -2.5 V at the outputs.

But when I connected those nodes at the supply pins for an OPA365, the negative voltage pin remains at 0 V, while the positive does go to 2.5 V. So my opamp only swings in positive voltages.

Any tips?

Thank you and kind regards

Hi Luiz,

Unfortunately, we cannot recommend or provide modeling support for third party tools.

You can use the TI Pspice and let us know if you have some problems.

Regards,

Febin

Hi there Febin,

So could you please provide me the complete schematic you used for the simulation? Maybe it's a problem with the values of capacitance or something, so the solver is not convering. I want to replicate your curve.

Thank you and kind regards,

Luiz Guilherme Enger

Hi Luiz,

This is the schematic I used for start-up simulation. I also suggest to remove any comments in the pspice netlist that is unique to the device. May be this helps. 

Regards,

Febin

Hey there Febin,

I build the exact same schematic and still can't run a transient analysis. I get this error message:

where node N00622 is the node at C1- and N01191 is the node between COUTP and RESRP.

Hi Luiz,

Unfortunately, we cannot support third party tools. 

Could you try using Pspice for TI?

Regards,

Febin

Hello Febin,

Well, that is a screenshot from the simulation suite included in PSpice for TI.

Hi Luiz,

Sorry for the late reply. I was on vacation.

Could you please tell me what changes you made to the original design? 

I could run the pspice model on ti.com and there was no error. 

Regards,

Febin

Hi Luiz,

I think re-installing is a good idea. Because I tried all the simulations and it works for me and so should for you.

You can always open a new thread for any support in the future.

Regards,

Febin