Simulating the TL494 in LTspice allows engineers to verify switching frequencies, PWM dead time, and output regulation before prototyping. By using an imported .sub model, you can effectively simulate complex power supply designs using this classic, versatile PWM controller.
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TI provides official PSpice models on the TL494 product page. These models are generally compatible with LTspice.
: Output frequency equals the oscillator frequency.
Outputs are active low, push-pull or open collector E_PWM 130 0 VALUE IF(V(7,9) > V(6,9), 0, 5) R_PWM 130 0 1MEG tl494 ltspice
The real utility of simulating the TL494 lies in tuning its dual internal error amplifiers for closed-loop voltage or current regulation. Error Amplifier Configuration
: Contains a frequently referenced .sub file for the TL494.
When mapping your schematic symbol to the underlying SPICE subcircuit code, ensure the node sequences match perfectly. Misaligned pin assignments will cause simulation errors or convergence failures. Pin Number Description / SPICE Function Non-inverting input of Error Amplifier 1 2 Inverting input of Error Amplifier 1 3 Compensation/Feedback input; monitors error amp outputs 4 Dead-Time Control input; sets minimum blanking time 5 Timing Capacitor connection for the internal oscillator 6 Timing Resistor connection for the internal oscillator 7 Circuit Ground 8 Collector terminal of Output Transistor 1 9 Emitter terminal of Output Transistor 1 10 Emitter terminal of Output Transistor 2 11 Collector terminal of Output Transistor 2 12 Main Positive Supply voltage input 13 OUTPUT CTRL Mode Select: Ground for single-ended, VREF for push-pull 14 Internal 5.0V reference regulator output 15 Inverting input of Error Amplifier 2 16 Non-inverting input of Error Amplifier 2 3. Setting Up the Core External Components
Feedback input (pin 5) overrides if lower D_FB 5 6 DCLAMP .MODEL DCLAMP D(Vfwd=0.7) Simulating the TL494 in LTspice allows engineers to
: Alternatively, you can keep the files in your project folder and add a SPICE directive to your schematic: .include TL494.sub 2. Functional Pins and Modeling Considerations
values for a specific frequency, or if you would like an example schematic for a topology. Share public link
Set 0 to start saving from the beginning.
, does not provide an official SPICE model for this specific IC. To get a working simulation, engineers and hobbyists often rely on third-party models or custom workarounds. Finding and Importing the Model Since there is no native model, you will typically find files provided by the community on forums like How to Add a Third-Party Model: Download the File : Look for a (library) or (model) file specifically for the TL494. Generate a Symbol This link or copies made by others cannot be deleted
While LTspice excels at capturing electrical transients, loop stability, and switching behavior, it is purely an electrical network simulator. It cannot compute real-world physical design variables such as component heating, thermal dissipation profiles, or magnetic core saturation limitations. Always complement your simulated findings with physical bench testing on a prototyping PCB. Next Steps
Output steering: C1 and C2 (pins 10,11) are collector outputs
Connect and CT (e.g., 1nF) to set the frequency (
