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UCC256404: Full bridge LLC Resonant

evanus yupiter
Prodigy 160 points
Part Number: UCC256404
Other Parts Discussed in Thread: UCC25600, UCD3138, UCD3138ALLCEVM150, UCD3138A, TIDA-01494

Hi all

I have power supply project around 1k5watt output power. I've ever consider to use phase shifted topology, but the primary inductance for my application will be around 2.2mH ( i use SLUC222D.xlx ) which is around 10 times bigger then desired primary inductance in LLC full bridge. 

Than i consider to use UCC256404 but due to the power needed, around 1K5 watt, i consider to use full bridge instead of half bridge. Unfortunately, UCC256404 have Vcr pin to detect the resonant cap voltage to ground, which is not suitable for full bridge topology, since the capacitor will not connect to ground anymore. 

How to use ucc 256404 for full bridge LLC? Or do TI have suitable LLC resonant controller that is suitable for full bridge topology?

thanks and regards

evan

  • 0
    TI__Mastermind 26495 points

    Hi Evanus,

    Thanks for reaching out. The resonant capacitor voltage and resonant current would need to be translated down to ground referenced signals for the controller to understand. There is the additional challenge of translating the HO gate signal to a ground referenced signal in order to drive the low side of the other half bridge. I would say UCC25600 is a better fit for full bridge LLC for analog control. It is a direct frequency control LLC that has two ground referenced gate signals. It will be much easier to realize a full bridge with UCC25600 compared to UCC256404.

    If digital power is on the table, the you can consider UCD3138 or C2000 for full bridge LLC. Both have examples on ti.com for realizing full bridge LLC. 

    Best Regards,

    Ben Lough

  • 0 in reply to Benjamin Lough
    Prodigy 160 points

    Hi Ben

    Thanks for your suggestion. When i read UCD3138, i think, it's a kind of mcu with some dedicated hardware inside for power application purpose, so i assume it need some programming in c/c++. (i suppose it use CCS), but i also find, it has Fusion digital power studio.and designer. What does those 2 fusion tool purpose? Does it mean, by using fusion digital power studio, we do not need to do c/c++ programing using CCS?

    Btw, i have tried fusion digital power designer, but i can't find UCD3138. UCD 3138 can only be found in fusion digital power studio, though some UCD3181 apps notes still mention fusion digital power designer

    If we can use fusion digital power studio, instead of doing c/c++ programing using CCS, is the feature in the default firmware as same as UCD3138ALLCEVM150?  Since i want to use full bridge LLC topology, how to configure the second leg bridge ( i assume the firmware use the same pwm output for the first leg as same as in UCD3138ALLCEVM150 ). 

    In the Fusion digital power studio, LLC model, i can't find a field to fill the value of Rsense (current sense), R & C for setting the gain and filter for the op amp that will amplify the current value (These field can be found in the PSFB), so how to enter these value, since these value also have some impact to the control loop response ?

    When will Totem pole PFC available for UCD3138A digital power studio ?

    Thanks and regards

    evan

  • 0 in reply to evanus yupiter
    TI__Mastermind 26495 points

    Hi Evanus,

    I have asked a UCD3138 engineer to comment on your questions.

    Best Regards,

    Ben Lough

  • 0 in reply to Benjamin Lough
    TI__Genius 14570 points

    Hi, Evanus,

    R1 and R2 (shown below) are used to program output voltage feedback scaler, and it affects loop gain or model. The current amplifier is not used for LLC modeling. 

    Fusion Digital Power Studio is firmware development tool for user to  develop their own firmware, which can download firmware, make some configuration changes. TI provides EVM as platform enriched with many features, but customers need write codes for their specific application by using CCS as compiler. 

    I hope it helps,

    Thanks,
    Sean

  • 0 in reply to Sean Xu
    Prodigy 160 points

    Hi Ben and Sean

    My project need current loop as well, i want to develop Li-Ion bat charger so, need both voltage and current loop, similar with TIDA-01494, but now in full bridge configuration. 

    From your explanation, I can use Fusion digital power and no need any coding, if i use exactly the topology used in the Fusion, but i can still modified and compiled using CCS.

    Thanks for your explanation

    regards

    evan

  • 0 in reply to evanus yupiter
    TI__Genius 14570 points

    Hi, Evan,

    UCD3138ALLCEVM150   is half bridge LLC, and but it is easy to expand to full bridge LLC. The firmware of this EVM can't be directly used for your battery charge. You need modify the firmware for battery charge.

    Regards,
    Sean