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interleave forward with SR control

MD Home
Intellectual 840 points
Other Parts Discussed in Thread: UCC28250

Dear E2E Community.

we are looking for interleave forward with SR controller in order to get high efficiency at out put power level ~ 400 - 600W.  Does TI have application note on how to use  UCC28250 configulation for 2SW forward converter?

  • 0
    TI__Guru 73595 points

    I assume "2SW forward" in your message meaning two-switch forward. If otherwise, please explain its meaning. If my understanding is correct, I have the below comment.

    UCC28250 is used to make PWM control in power converters such as symmetrical half-bridge and push-pull. But on a typical two-switch forward, as I know its configuration should be as shown as in the below figure, the two switches Q1 and Q2 are controlled to turn on and turn off at the same time. Then I do not feel clear how to use UCC28250 in this topology. If you have different description referring to "2SW forward" or some idea to use UCC28250 in such an operation, please describe it then we can discuss how to use UCC28250 on that basis.

    An article describing typical two-switch forward converter operation can be found through this link:

    http://www.eetimes.com/design/power-management-design/4012212/Two-switch-topology-boosts-forward-flyback-designs

     

  • 0 in reply to Hong Huang
    Expert 1260 points

    Hung,

    I mean 2 converters work in pararell, each converter configuration as 2 switch forward which can disable 1 converter if load reduce(~ half load). our target is lowest cost, 80+ efficiency over load range, output power~ 500W. Or do you have any suggestion?

  • 0 in reply to Knighty Nimp
    TI__Guru 73595 points

    It does not seem UCC28250 one of its two primary side drivers (OUTA and B) can be disabled. So to cut off one converter at half load, some additonal circuit will be needed. But as you only use one control IC there may be some savings on the controller to be used. But the real cost budget may need some more detail on the design.

    It is obvious two controllers can be used. Again, the system cost needs some more detail and I am not sure one controller cost saving will make the whole system cost always lower or lowest.

     

  • 0 in reply to Hong Huang
    Intellectual 840 points

    Hung,

    Yes I mean two controllers work in pararell(Interleaved Forward)and still need syncronous rectify on the output side to improve the efficiency. Do TI have reference design how to configure UCC28250  as interleave forward?

  • 0 in reply to MD Home
    TI__Guru 73595 points

    UCC28250 can be used to make input phase interleaved to the two converters. The converters are in half-bridge or push-pull configuration in which UCC28250 provides control-driven SR drive signals to the secondary side. This is what it means the interleaved forward.

    For the single-ended forward or two-transistor forward, UCC8250 may not achieve control-driven SR to the secondary. 

  • 0 in reply to Hong Huang
    Intellectual 840 points

    Hung,

    Thnaks, sorry my massage not clear enough I should say "interleaving implementations for forward"I attached my concept design in attached.

    - Can UCC28250 control 2 converter(with SR) as attached?

    - if not, as you stated above what is your recomment to control these concept design?

    Thank in advance.

     

  • 0 in reply to MD Home
    TI__Guru 73595 points

    I think you can use one UCC28250 to control two forward converters with OUTA controlling one and OUTB controlling the other. But you would need external circuit to disable OUTA or OUTB at light load since UCC28250 does not have a feature to disable OUTA or OUTB individually. Also when load becomes heavier, the disabled converter will be turned on while it will be turned on right away and there will be no soft start as OUTA and OUTB were not disabled.

    If you are willing to add external circuit to achieve the features needed, it would be ok to use UCC28250.

    Otherwise, let me know and I will provide other suggestions.

  • 0 in reply to Hong Huang
    Intellectual 840 points

    Hung,

    yes, we considering external circuit to disable one converter. It better if you can provide interleave forward referece design base on UCC28250.

    Thanks.

  • 0 in reply to MD Home
    TI__Guru 73595 points

    On your request of a referece design, please contact our local sales office and technical support in your area.

  • 0 in reply to Hong Huang
    Intellectual 840 points

    Hung,

     

    I just need reference circuit. Does it avaliable on TI web(as checked do not have)? so that we will modify base on UCC28250EVM-501 .

    Thanks.