I am attempting to simulate a flyback controller from TI, part number UCC28700-Q1, datasheet here: http://www.ti.com/lit/ds/symlink/ucc28700-q1.pdf

I have downloaded the SPICE model from TI (as can be found here: http://www.ti.com/lit/zip/slum455) and am now attempting to build a SPICE simulation in LTSpice.

If I open the model in LTSpice, I can right click the .SUBCKT line and let LTSpice auto draw the symbol for me. When I do so, I get a 6pin block with the pins labelled as: P1 P2 S1 S2 RS1 RS2. These pin names do not match up with anything I can see in the datasheet, and I don't believe that the order of the pins matters in terms of relationship between SPICE model and real world. If I try and draw the symbol myself, I end up with the same issue, as I still don't know how these pin names relate to the signals.

Is there a simple way to work out which pin is which?


1 Answer 1


"P" is for primary. "S" is for secondary. "RS" is apparently for reset winding. This is a model for a transformer they used with the IC in their demo circuit.

The models for the actual IC seem to be in some kind of encrypted form, so they'll only work with PSpice, not with LTSpice.

  • \$\begingroup\$ TI often provide encrypted models for OrCad (not much use in LTSpice, though, as you note). \$\endgroup\$ Commented Aug 14, 2016 at 16:41
  • \$\begingroup\$ @PeterSmith, IIRC the file has the text "PSpice" in it near the beginning. \$\endgroup\$
    – The Photon
    Commented Aug 14, 2016 at 18:22

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