Question on TPS5450

TPS5450 cannot support the buck and boost topology.  The minimum Vin must be greater than Vout (plus some headroom).

Thanks John,

How much head room is usually needed? Any suggestions on a suitable part in this case? How about restrict input to 12V~14V?

You probably need about 1 -1.5 V of headroom.  You could probably get by with less using a synchronous converter such as TPS54622.  You also might try putting your preferred input and output conditions into Webench and see what that tool recommends.  If it does not return anything, then try raising your lower Vin limit.

Thanks John, another questions, how can I make Ti-TINA work with a pre-build TI examples? Also it lacks enough components to build meaningful circuit, and I can't find descriptions to build a model.

What kind of problems are you having?  I don't really use TINA all that much, but I have run some sims with it.  There are pretty much all teh passive components you would need to go with or modify any model you download to match your actual configutation. 

The reason I use TINA, is because it has pre-build TI DC controllers already.  I tried to run the pre-built TPS5450 module; the issue I encountered was "Operating point not found" pointing to a Shottkey diode.  In general, it would be easy to build passive components from spec sheet?  Also, any other particular circuit simulation package TI recommends? Thanks John..

Did you use the "reference design" or "transient model"?  I might give it a try if I get a chance tomorrow.

It's the TPS5450 TINA-TI Transient Reference Design. Also are the PSpice Models only for the PSpice before it was taken by Orcad? I am setting up the SwitchPro as well.

Are the TINA-TI Transient Spice Models portable to Spice based simulator?

Thanks.