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UCC256404: 3.3KW || DC-DC || 54Vout || Synchronous Full Bridge LLC.

rizwan ali1
Prodigy 70 points
Part Number: UCC256404
Other Parts Discussed in Thread: UCD3138, UCD3138A, PMP21842, UCC25660

Hi TI Team,

I am going to design 3.3KW DC-DC power supply with following specification.

Pout - 3.3KW
Vout - 54V - 96V_dc
Iout max - 61A_dc
Vin - 390V - 410V_dc
Topology - FB_LLC with synchronous full wave rectification.

Kindly reply the following queries.

a. Can I use this UCC25640x IC in full bridge LLC also?
b. (if not) Please suggest appropriate IC for synchronous full-bridge LLC meeting above mentioned specification
c. Please provide the calculation sheet or design guide also.

Regards,

  • 0
    TI__Mastermind 44620 points

    Hi Rizwan,

    Our Power Design Services team has just released PMP22951 which is very close to the above requirements. \

    I hope this helps to get you started.

    Regards,

    John

  • 0 in reply to JCHK
    Prodigy 70 points

    Hi John,
    Appreciating response,

    Unfortunately it is full bridge phase shift while I am looking for Full bridge LLC. Could you please help me here?

    Regards,
    Rizwan

  • 0 in reply to rizwan ali1
    TI__Mastermind 44620 points

    Hi Rizwan,

    We do not have an analog Full Bridge LLC solution at the moment. We do have a reference design PMP21842 which uses the UCD3138 to implement a full-bridge LLC. This is only a 500W design but could be a good starting point.

    Regards,


    John

  • 0 in reply to JCHK
    Prodigy 70 points

    Hi John,

    Thanks for the reply.

    This is something considerable. Could you please share me its design guide for the calculation or excel tool So, that I can scale it to 3.3KW?

    Regards,

  • 0 in reply to rizwan ali1
    TI__Mastermind 44620 points

    Hi Rizwan,

    I have looped in an expert on UCD to help you with this.

    Regards,

  • 0 in reply to JCHK
    Prodigy 70 points

    Hi John,

    appreciating response,

    will be waiting for the experts support.

    Regards,

  • 0 in reply to rizwan ali1
    TI__Expert 5615 points

    Hello Rizwan,

    Due to your wide output voltage range, Full-Bridge LLC is not recommended for your design. A PSFB is more suited for a wide voltage output range at high power. 

    A FB-LLC revolves around a resonant tank, which is designed for a specific frequency Fsw (Ex. 100kHz). Your turns ratio will determine what the output voltage is. So, if you have to convert from 390V to 75V, your turns ratio is 5.3. Now that you are at 75V, you need to be +/-21V to achieve your range. To do this, your controller's switching frequency either goes up for the output voltage to go down, or goes down for the output voltage to go up. However, since the resonant tank is not designed to deviate frequencies, your efficiency will decrease. We typically only see an output voltage deviation of at most +/- 10%. 

    If you must use FB-LLC, then the UCD3138A is a good choice since it includes SR control and you can program the switching frequency. See the below parameters in Power Stage Designer (https://www.ti.com/tool/POWERSTAGE-DESIGNER). You can use the calculated values from Power Stage Designer to scale up your design from the PMP21842. Then, you can vary the switching frequency in the firmware to achieve your target output voltage. This changing switching frequency could also be triggered by an external signal, such as I2C or UART, from another MCU.

     

    If the power level does not need to be as high, then the UCC25660 could work. The UCC25660 can achieve a wide output voltage range with it's Input-Power Proportional Control (IPPC) scheme. However, it is a Half-Bridge LLC controller and thus will require gate drivers out of sync from each other. Something like the below diagram might be possible. The UCC25660 is a new product so we would not have any design resources if you chose this unconventional route.

    Regards,

    Jonathan Wong