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UCC28061-Q1: Some questions

Hirotaka Matsumoto
Guru 27545 points
Part Number: UCC28061-Q1

Hi all

Would you mind if we ask UCC28061-Q1?

We are sorry that we have some basic questions as follows;

<Question1>
On the datasheet P15 Figure21, what do KT, KTA and KTB indicate?
Could you let us know formulas for KT, KTA and KTB?(We could not find it.)

<Question2>
Could you let us know what the datasheet P15 Figure21 indicate?

<Question3>
Could you let us know what "Phase B to phase A on-time matching" is used for?

Kind regards,

Hirotaka Matsumoto

  • 0
    TI__Mastermind 34465 points

    Hello Matsumoto-san,

    Sorry that these parameters are causing an issue but I will try to explain as best I can.

    The UCC28061-Q1 has an interleaved dual switching converter phase A and phase B.
    The gain of the error amplifier is KTA for phase A and KTB for phase B.
    For design purposes KTA = KTB = KT
    The value of KT is given in the datasheet Figure 19 page 14
    This is confusing labelled KTL but KTL is actually KT

    In an real design the gains of the A and B amplifiers are not exactly equal and the phase difference is not exactly
    180 degrees between A and B phases.
    Figure 21 shows the gain error that results when there is a slight shift in phasing.
    You can see there if there is an increase in gain for A then there is a decrease in gain for B.
    And this all happens because of a slight shift in phase from the ideal 180 degrees.
    This would be happening because of pcb layout and noise pickup in the actual design.

    Your last question is about "on-time matching"

    This is a parameter specified in parametric table page 6 of the data sheet.
    We specify this as -6% to +6%
    For design purposes gate drive GDA is the same pulse width as GDB but in real world parts there is a 6% tolerance in these gate drive  widths

    Hope this answers your questions

    Regards

    John