Trying to simulate LM43601 webench design with PSPice for TI

Hello Jasper,

are you utilizing the inverting model. The nodes of the ckt model for the power converter is changed up a bit for inverting buck boost designs.

Thanks for your answer!

In the Model it says "Model functionality is corrected to make compatible for IBB" and that the reference voltage is gnd and not 0V. So I guess it should work. Also on the product site the PSPice model is described as non-inverting and inverting.

I also tried bootstrapping the input supply between input and output as described on page 9: www.ti.com/.../snva856a.pdf

But it didnt work.

On the model I can change the mode, which is set to 0 by default, but I cant find anywhere what this mode means. Does this have something to do with inverting?

I think I will just stick to the inverting reference design which is working fine for me.

I tried replacing the values of the reference design with the one from the webench design but it didnt work aswell.

Hello Jasper,

Are you looking to optimize the reference design?

What are specifically looking to do...perhaps I can help?

Thanks for your offer to help!

Actually I have a few points where I am stuck.

The Webench design had a Iout of 1A. The inverting reference design is only working until 0.7A. This would be ok but I would prefer 1A.

Also I cant get the sync to work with the inverting reference design. With the non-inverting reference design its working, but not with the inverting one. I would like to sync it to a 1Mhz 3.3V clock.

I have attached the schematic:

7608.LM43601_Schematic.pdf

Hello, thank you for the appnote!

I hope its ok to bother you once again. I see what you are saying, however I cant really get it to sync properly. I have now used a 3.3V clock source referenced to AGND of the LM43601 as stated in your appnote. Shortly after applying the sync signal the switching stops. However, when its just running at 1Mhz just with the RT resistor and without a clock its fine. Only when applying the 1Mhz clock signal its collapsing.

LM43601_Transient_6.pdf

LM43601_Transient_7.pdf

LM43601_Schematic_3.pdf

Thanks for your help!