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UCD3138A64: Basic example code for PSFB

Part Number: UCD3138A64
Other Parts Discussed in Thread: UCD3138,

Hello everyone,

I am trying to build a PSFB using the UCD3138A64. However, quite surprisngly I am not able to find any example codes for the same. Unlike C2000 controllers, where after explaining each section, TI gives nicely commented example code, I can't find anything similar on the UCD3138 side. Yes there are reference desings avialble but they do little to help a beginner who has just started the UCCD3138 coontroller. A full fledged project is much more difficult to keep track of and understand especially when TI says that a detailed manual is provided, which, without a doubt, is missing. The user just has to depend on the few shortly commented lines of code.

I would request TI represenatives to create a a proper examples for each part of the reference manual( similar to the C2000 devices). Much of the potential of the device is lost without example codes. 

For now, I would be grateful if someone could send me a basic example code for the phase shifted full bridge. I just want the basic configuration in the open loop mode, to which later I can change the phase shifts later through the Hyperknob in the memory debugger.

  • Pramod, the UCD is a different type of device from the C2000, and we have a different approach to the learning curve.  We recommend looking through and ideally running the labs for the UCD, which can be found listed in this E2E post:

    The labs go through a sequence to bring up a power supply, and introduce the elements of the device and our standard programs.

    We also suggest reading through the UCD3138 Technical Reference Manual, It's at:

    It will tell you what is available in the UCD.  You need to just skim it, not memorize it.  

    With that background, it should be easier to understand the PSFB EVM code, which is here:

    If at that point you want to understand the nasty details of how the DPWMs are set up for the PSFB, you can friend me on the E2E forum, and send me your email, and I will send you an outdated, unpublished app note that does a fairly good job of explaining what's going on with the details.  

  • Hi Ian,

    I have already gone through the technical reference manual for the DPWM. 
    I have also seen the labs for the parts which are required in the open loop mode. 

    And yes, I would want to understand the details of the code in the EVM. If there any other application notes or code examples other than the one which you mentioned, which could help me for learning the UCD3138, I would request you to send it to me. 

    I would also request you to send the application for the LLC EVM.

    Thank you 

  • I've emailed the application notes on the LLC and the PSFB.  You may also want to look at the HSFB EVM.  The PFC has a faster interrupt because the voltage loop and Power Factor Control are done in firmware.  It does have the newest version of the PMBus firmware.  

    I suggest looking at the UCD3138 Practical Design Guideline, although it's mostly about hardware - things like layout, grounding and filtering of the power supply to the UCD.  You need to do a good job of those tasks, otherwise the UCD won't run well in the unfriendly environment of a switching power supply.  

  • Hi Ian,

    I am grateful to you for sending out the application notes. As per your suggestion, could you then also mail the HSFB and PFC firmware specific application notes? It would help me learn a thing or more from each one of them and speed up the development process.

    I would look into the UCD design guidelines later when I am actually building the supply. For now I am building a barebones open frame setup with the UCD3138 open loop evaluation kit.

    Thank you 

  • I haven't found the HSFB and PFC firmware manuals.  I stil think I can find them, but they get less use, probably because the PFC and HSFB are more straightforward as far as the UCD is concerned.  The PSFB and the LLC do more difficult things with the DPWM.  I'll try to look some more tomorrow.  

    I know also that since the application is somewhat simpler, the app notes aren't as detailed.  

  • Thank you Ian for your efforts. I will be opening a seperate thread for firmware related doubts. In the meanwhile if you are able to find the other application notes then please let me know.

  • I'm going to stop looking for the other firmware recipes.  They're not that useful.  We didn't put nearly as much effort into them because the UCD configuration is not as complex and hard to understand.  You should get enough info from the two you've got , and from asking questions on the forum.  I also suggest trying a search on the forum, either using the built in search, or google may actually be better.