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WEBENCH® Tools/UCC256304: UCC256304

Thomas Flack
Prodigy 100 points
Part Number: UCC256304
Other Parts Discussed in Thread: UCC256404

Tool/software: WEBENCH® Design Tools

Hi Forum Members,

I am new to the WEBENCH forum and wish to seek some help. I design power supplies and have done so for awhile. My recent designs are LLC topology and I have so far done an excellent job. I have 500K units in the field with very small failure rate. My last design was using SSL4120 from NXP. NXP is no longer in the power supply device market anymore and I have turned all my attention towards TI. I did use the NXP tool when they were in the business but its gone now. I only use NXP because nine years ago they were the only semi manufacture to offer a totally inclusive LLC Controller device; PFC, HBC and FET drivers all in one device.

NXP was then, this is now, I am aware that TI has WEBENCH and I want to learn to use it.I am also very aware that TI has a great LLC solution as well.

Here is where I would need a little help. The most difficult step in designing power supplies is in the LOOP analysis for the design. Many compensation loops can be modeled. I would like to know if I could model a OTA Transconductance Feedback loop in WEBENCH. I am aware of how to do this when the OPAMP is external to the device. Simply calculate the voltage to current ratio for the feedback resistor and add the feedback capacitor via calculation for the bandwidth of interest.

I see some controllers where the OTA is internal to the SMPS controller allowing OTA an output pin only. This type of OTA will need to have the additional compensation feedback components to be attached on the output PIN of the internal OTA. These additional compensation components are attached externally to the internal OTA output, the components in the loop are typically a resistor in series with a cap to ground along with a single cap to ground which is in parallel with the series branch.

I would like to model this INTERNAL OTA within WEBENCH and see the BODE plot. Is there a reference example I could review. Any input is appreciated.

Next, I am looking at the TI UCC256304 device. This device device is also an LLC Controller. I found document SLUSD60. The design procedure starts on page 49. It starts with WEBENCH and I do understand all of these equations. At the end of this design doc there is a Design Spreadsheet on page 65 called "UCC256304 Desgin Calculator, UCC634." I cannot locate this spreadsheet.

Has it been removed as WEBENCH should be the dominate tool, or is it still good to have. If so where can I find this spreadsheet?

Thanks for the help.

  • 0
    TI__Expert 8210 points

    Thomas

    I'm glad you are considering TI for your next LLC design.

    First off I'd like to recommend that you use UCC256404 instead.  This is a newer device that is pin-to-pin compatible with the device you previously looked at but has several improved features.  Details are in this app note http://www.ti.com/lit/pdf/slua966

    Webench does not support loop compensation design.  For feedback compensation design, our SIMPLIS simulation model http://www.ti.com/lit/zip/slum684 

    Best Regards,

    Eric

  • 0 in reply to Eric Faraci
    Prodigy 100 points

    Hi Eric,

    Thanks for getting back to me. I will review what you have sent. In my new design I will be designing an LED Controller system for a new product on my schedule. During my research in designing loop compensation systems, and searching for the proper tool, I went back to looked into the MATHWORKS Inc solutions. I was pleased to locate a design in MATHWORKS that almost meets my new design goals 90%.

    The good news about this presentation is, it uses a TI Eval Board and the presentation is called "Designing Efficient Dc-to-DC Power Converters". Please take a look. This MATHWORKS flow allows the user to perfectly tune the design through MATLAB-Simulink toolboxes and then generate the C-Code for Code Composer Studio directly within MATLAB then into the TI CPU. There is some toolboxes I need to download from TI that fit into the MATLAB/Simulink Library. These TI Toolboxes includes all the code to be directly ported to this eval board I just mentioned. I have to quickly purchase this board as there is only one in stock.

    This presentation uses the TMDSDCDCLEDKIT and contains the C2000 PICCOLO processor. I own MATHWORKS r2013a and the presentation shows a flow for designing into the TI CPU. I also use Code Composer Studio for the MPS430 device. I'm actually going through the 650 page MSP430 Workbook, I'm presently at page 314, but far enough along to know how to use Code Composer Studio.

    This seems to be the way I will go as MATHWORKS is very powerful tool and will even allow me to the import the FET parameters into MATLAB for a really clean design.

    So, my first question I need to ask you, are you knowledgeable in using MATLAB/Simulink in this way. Next, I need to learn how to get the Toolboxes from TI that will drop into the MATHWORKS/Simulink tool.

    I hope you can direct me to where these ToolBoxes are. I will start searching myself. You can give any details that I should know.

    Thanks a heap for TI lining itself with MATHWORKS, that was brilliant!

    Regards,

    Thomas Flack

    Senior Design Engineer

  • 0 in reply to Thomas Flack
    TI__Expert 8210 points

    Thomas 

    For UCC256404, the only simulation tool we have is a SIMPLIS model that is available here http://www.ti.com/lit/zip/slum684.  We do not have any toolbox that is designed to be imported into MATLAB/Simulink with this device.

    If you have a question on MATLAB/Simulink with a different TI device (such as a C2000 digital controller), I recommend you post a separate E2E thread to make sure the proper expert at TI responds to your question.

    Best Regards,

    Eric