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UCC28951-Q1: UCC28951-Q1

Rajashekar Koutla
Intellectual 590 points
Part Number: UCC28951-Q1
Other Parts Discussed in Thread: UCC28950, TINA-TI

Hello sir ,

My power circuit design for dc dc converter of 1.3KW is linked belowpower circuit.pdf

On the secondary side of centertapped  transformer , the two source terminals of two mosfets are connected with the output inductor and the center tapped wire is connected to the ground. will you please clarify me whether the connection is correct or not ??

And I found that the connection which made in the reference design sheet of 600W dc dc converter using UCC28950  is reverse of mine circuit connection on the secondary side of transformer .

Please clarify..

Thanks

  • 0
    TI__Mastermind 25570 points
    Hello Rajashekar

    Your connections on the secondary side are incorrect. For example, imagine QA and QD are on. The drain of QF will go negative of 0V out and during the QA/QD Ton, QF is also on. I think that this arrangement will generate a negative output voltage but I'd have to simulate it (or think about it more closely) to be sure. You should reproduce the arrangement shown in the Typ App diagram on page 1 of the DS.

    I would also recommend that you download the TINA-TI reference design for this device - you can find it on the website www.ti.com/.../getliterature.tsp . I'd first simply familiarise yourelf with it by getting it to run for you without any changes, then make the changes you need.

    Regards
    Colin
  • 0 in reply to Colin Gillmor
    TI__Mastermind 25570 points
    Hello Rajashekar

    I forgot to mention that you should double check the frequency response of the Hall effect sensor you are proposing to use for current sensing. You will need a bandwidth sufficient to replicate the current waveform, I'd estimate a 2MHz bandwidth for a 100kHz switching frequency (that's just an estimate by the way - please verify that it is ok before making any final decistions). Hall effect sensors also need a power supply to operate them and you will need to make certain that the Hall effect sensor is active before the UCC28950 and that it continues to operate until the UCC28950 is turned off.
    A further problem is that Hall effect sensors are also sensitive to DC magnetic fields - including the Earths field. Their output can vary as the device is rotated relative to the Earths field - you need to scale the system so that this is not a significant issue for you.

    I'd strongly recommend that you use a current transformer - unless you have a good reason to prefer the Hall effect sensor.

    Regards
    Colin