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  • UCC256402: PFC+2LLC power stage

    TI Thinks Resolved
    Part Number: UCC256402 Hello, Below is attached block diagram of the power stage. My question is, would there be any problem if two separated LLC stages share one PFC input. Considering that if both upper switches are open at the same time both resonant tanks…
    • Answered

  • UCC256402: UCC256402 - Switching Frequency Question

    Resolved
    Part Number: UCC256402 Question 1: During the soft start of this IC [UCC256402], if C1, the upper voltage divider capacitor, is adjusted from C1=47pF to C1=100pF, why does the soft start frequency decrease? If the C1=47pF then fs = 510kHz; C1=100pF then…
    • Resolved
    • Answered

  • UCC256402: External MOSFET Driver

    Resolved
    Part Number: UCC256402 I would like to use an external driver to reduce the dissipation in the UCC256402 and reach higher frequencies. According to the datasheet the HS pin is used as a reference for the dead time, so I assume that i should not connect…
    • Resolved

  • UCC256402: UCC256402: Soft start issue

    Part Number: UCC256402 Hello, https://e2e.ti.com/support/power-management-group/power-management/f/power-management-forum/1244602/ucc256402-soft-start-issue?tisearch=e2e-sitesearch&keymatch=soft%20start%20UCC256402# Further to our discussion soft…

  • UCC256402: Transformer dot convention and synchronous rectification

    Part Number: UCC256402 Other Parts Discussed in Thread: UCC24624 Hi, I have a correctly working 72V to 14.5V LLC convertor design with UCC256402. Here is the output section of it. Its output rectifiers get verry hot. So I added synchronous rectification…

  • UCC256402: Output Voltage varies with input voltage.

    TI Thinks Resolved
    Part Number: UCC256402 I'm currently working with 72VDC to 14.45VDC converter. My previous design working well, instead output rectifiers heating. So I added a SR controller with MOSFETs. My new design not working as expected. I checked my new rectification…

  • UCC256402: Application problem.

    Part Number: UCC256402 Hi, Vbulk is the rectified bus voltage, Vin=170-300Vac. When Vin=170-280Vac, it is good. However, when Vin=290Vac~300Vac, the input voltage is energized for the first time and there is no output voltage; Then turn off and power…

  • UCC256402: Resonant inductor is heating

    TI Thinks Resolved
    Part Number: UCC256402 Hi, I'm developing a 550W LLC resonant converter for converter 72VDC (IN) to 14.40VDC (OUT). and c22 c23 are the 2.2uf resonant caps. The resonant inductor is L1 0.6uH MPC075LR60C. trans primary winding is 7.7uH and Np/Ns = 2.5…

  • UCC256402: Soft start issue

    TI Thinks Resolved
    Part Number: UCC256402 Hi we are using UCC256402 LLC Controller for our 200W project(28V output) we are having problems with soft start. At initial condition the slope is very high it is rising upto 20V within very less time. we tried different combinations…

  • RE: UCC256402: Help with Optocoupler Feedback Network

    Hi Marcel, Could you share the waveforms. Is the controller going into fault mode? After you change the BMT values, are you seeing the issue at all loads or only at no load? Regards Manikanta P

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