LMR23630: Zeta Converter Buck/Boost implementation

Antenna_Head

Part Number: LMR23630
Other Parts Discussed in Thread: TPS5430, LMR23625,

Please find attached simulation showing an implementation of a Zeta Buck/Boost Converter having 10V < Vin < 13V, Vout = 10V, Iout ~= 1A.

The simulation is based on the TPS5430 (and it's TINA Reference Design) because it has a TINA model that may be used in the inverting buck/boost configuration. This simulation runs quickly, in about 30 seconds.

D1/C3 are the inverting buck/boost components, and C5/D2 are the Zeta specific rectifier and power transfer capacitor to make it operate as a non-inverting buck/boost. I have not optimized any of the values, just threw this together to verify it would basically work.

I would like to use the LMR23625 or LMR23630 in this topology. As I am unable to simulate the LMR236xx devices in the Zeta topology due to limitations with its model, I am asking here if you see any problems operating it in this manner?

Thanks, Best, Steve

TPS5430 Zeta Converter.TSC

over 4 years ago

0 Neal Zhang over 4 years ago

TI__Expert 4720 points

Hi,

You can export TINA form Webench, then do simulation. I think LMR23630 is fine to use in this application.

0 Antenna_Head over 4 years ago in reply to Neal Zhang

TI__Genius 11605 points

Webench doesn't support either the inverting buck boost or the Zeta configuration when using the LMR23630.

The simulation model for LMR23630 available on the product page doesn't support inverting buck boost.

0 Neal Zhang over 4 years ago in reply to Antenna_Head

TI__Expert 4720 points

Hi Steve,

You can export Webench model to TINA, to get the IC model. Then you can configure it as buck boost.

https://www.ti.com/lit/mo/slvmay6a/slvmay6a.pdf

Besides, for your circuit, if you C5(10u), then it is a fly-buck-boost. I think it's better typology since it saves one cap. What do you think?

http://www.ti.com/lit/an/slva369a/slva369a.pdf

0 Antenna_Head over 4 years ago in reply to Neal Zhang

TI__Genius 11605 points

Neal-

Are you saying the Webench model is different than the one found on the product page?

Please see my earlier thread regarding building a fly-buck-boost with isolated output using LMR23625, https://e2e.ti.com/support/power-management/f/196/t/852030

I can try what you suggest, but I am wondering why the models would be different?

-Steve

0 Antenna_Head over 4 years ago in reply to Antenna_Head

TI__Genius 11605 points

Neal-

I used the model from Webench for LMR23625.

Good news: It seems to work in my Zeta Converter that I started this thread with.

Bad news: it DOESN'T work with the fly-buck-boost converter that I reference in my previous post.

I'll work on it some more, but it would be really nice to know what is wrong with the fly-buck-boost as well.

I have attached the Zeta converter.

-Steve

LMR23625 Zeta Converter.TSC

0 Neal Zhang over 4 years ago in reply to Antenna_Head

TI__Expert 4720 points

Hi Steve,

I saw your email, let's talk in email.

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LMR23630: Zeta Converter Buck/Boost implementation