) is configured via the components attached to (Pin 6) and CT (Pin 5). Use the standard formula:
After completing these steps, the TL494 component should appear when you add a component (press F2 ) in an LTspice schematic and navigate to the folder where you placed the TL494.asy file.
In one user’s troubleshooting, after updating to LTspice24, an existing TL494 model failed. The user had to manually correct several lines, including changing V§DT N007 DTC 0.12 to V1 N007 DTC 0.12 and correcting A4 0 OC 0 N008 0 0 N006 0 to A4 0 020 0 N008 0 0 N006 0 . This highlights the need to be comfortable editing the SPICE netlist directly to match the software’s evolving syntax requirements.
to name your PWM outputs, feedback nodes, and error amplifier inputs. Decoupling is Key tl494 ltspice
* TL494 Subcircuit for LTspice * Pin order: 1IN+ 1IN- 2IN+ 2IN- FB COMP CT RT GND C1 C2 VCC OUT1 OUT2 * Simplified functional model: oscillator, PWM comparator, error amps, outputs
: Many online downloads of the TL494 model contain a subtle but critical character corruption. A particular erroneous character § often appears in the netlist file. For example, you might see a line like V§DT N007 DTC 0.12 . This must be corrected to V1 N007 DTC 0.12 . Without this fix, the simulation will fail to run properly, as discussed in the following section.
The next time you reach for the TL494 datasheet, open LTspice first. With the right model and the knowledge from this guide, you’ll have your PWM controller simulated and optimized before building a single prototype. ) is configured via the components attached to
Error amplifier (single op-amp, high gain)
You can save the following code as a text file named TL494.sub and place it in your LTspice library folder (typically C:\Users\[User]\Documents\LTspiceXVII\lib\sub ) [1, 3].
Would you like an example LTspice schematic file (.asc) for a basic TL494 buck or boost converter simulation? The user had to manually correct several lines,
Set to 10n or 100n . A fine timestep prevents convergence errors caused by sharp digital logic transitions inside the macro-model. Click OK and place the .tran 10m directive on the canvas. Click the Run (Running Man) icon. 6. Troubleshooting Common Modeling Errors
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The TL494 remains a relevant and powerful PWM controller for a wide range of power supply applications. While Texas Instruments doesn’t officially support LTspice, the engineering community has developed excellent SPICE models that enable accurate simulation of this versatile IC.