Plot the 1IN+ and 1IN- pins to see how the feedback loop controls the duty cycle. 6. Tips for Successful TL494 Simulations
Move the symbol file ( tl494.as y) to the LTspice symbol directory: C:\Users\[YourUsername]\Documents\LTspiceXVII\lib\sym\AutoGenerated\ (or your specific LTspice installation path).
or f = 1.2 / (RT × CT) , depending on the model.
Complex subcircuits can cause convergence problems. tl494 ltspice
Place the TL494 subcircuit (requires creating a symbol from TL494.sub ).
: If you did not place the .sub file into the system directory, add the following text command anywhere on your schematic: .include TL494.sub Use code with caution. Running the Analysis
: A common source for unofficial but functional models. Plot the 1IN+ and 1IN- pins to see
Add a generic component (like dip16 ) and rename it to match the subcircuit name in the file (e.g., TL494 ).
: Programmable via an external resistor ( RTcap R sub cap T ) and capacitor ( CTcap C sub cap T
: If configured for push-pull mode, you will see alternating square waves. The duty cycle will be controlled by the voltage applied to the error amplifiers or the DTC pin. 6. Advanced Simulation: Closed-Loop Regulation or f = 1
The TI PSpice model uses charge-controlled switches. Add options reltol=1e-3 vntol=1e-4 to your simulation directive.
Another convenient source is the LTwiki. The “Bordodynov’s Electronics web page” available through the LTwiki main page contains the complete library of TL494 symbols and models. This is regularly cited in engineering forums as the go-to resource for TL494 LTspice models.