LMR36015: Accessing old Webench / LMR36015 Webench support

Hi Richard,

Could you please share with me the requirements of your circuit? I'll need the input voltage, output voltage, load current, operating temperature, and anything else about your old WebBench design that you can share. I will look into why the design did not run in WebBench, and try to get it running again. We cannot provide access to an older version of WebBench.

Best regards,

Ridge 

Hi Ridge,

It's not that the design won't run, the current version of Webench does not support the LMR36015.  The old one did.  I've attached a simulation I ran with the old one.  I'd like to re-run simulations because I'm seeing an excessive temperature rise.  I know that inductor size affect dissipation and wanted to experiment with different inductors.  When I tried to run the current simulator it gives me an error message " 

"   WBDesign66.pdf

I tried using Webench to design an inverting converter with the LMR36015A. 

I have a 24V input and want -17V output.  The voltage spread is 41V which is well within the voltage spec of the part.  

However, the Webench software will not allow an output voltage more negative than -5V.

Hi Richard,

Since WebBench only allows for a -5V inverting output for the LMR36015A, please refer to the following application note for designing your inverting buck boost converter: https://www.ti.com/lit/an/snva856b/snva856b.pdf

Hope this helps. Please let us know if you have any more questions.

Best regards,

Ridge Lahti

I already have that app note.  The whole idea of a simulator is to avoid having to do a detailed paper design and to catch any problems that might have been missed.

My question is why won't it allow a larger output than -5V?  The tool should allow setting the output to whatever voltage is desired.  The simulation would then show what's going to happen.  If there is a technical reason why that part shouldn't be used for more than -5V that should be reported.  Presumably it would show up in the simulation results.

Hi Richard,

WebBench only has certain output voltages for inverting buck boost because those are the ones we have tested. WebBench requires data from a real application in order to estimate the performance of a design. The datasheet and the "Working With Inverting Buck-Boost Converters" will be good guides for your design. For simulation purposes, there is an inverting PSPICE model for the LMR36015A. There is also an inverting example schematic for the LMR36015A within PSPICE for TI.

Best regards,

Ridge Lahti

Hi Richard,

I've tried using the schematic myself and was able to get it working for a -17V output voltage at 24Vin in PSPICE for TI. I've attached my schematic to this message. I had to extend the simulation time from the stated 270us to a few milliseconds to see the voltage reach -17V.

Best regards

Ridge

lmr36015a_trans.opj

Thanks.  I'll try getting it going.  I need to model the efficiency, not the basic operation.  I haven't done that in PSPICE before.