Use the TL494’s dual outputs with an alternating flip-flop for high-efficiency power stages.
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].
LTSpice is a free, open-source SPICE-based circuit simulator developed by Linear Technology (now part of Analog Devices). LTSpice is widely used by designers and engineers to simulate and analyze complex electronic circuits, including analog, digital, and mixed-signal circuits. The simulator provides a wide range of features, including:
: PWM simulations create steep, fast-switching edges that can choke the SPICE solver. To fix this, change your simulation options. Add the directive .options noopiter or alter the solver in your settings to Alternate ( Control Panel > SPICE > Solver: Alternate ). Error: Outputs are stuck low/high
: C:\Users\[YourUsername]\Documents\LTspiceXVII\lib\sym\AutoGenerated\ (or a custom subfolder). tl494 ltspice
Try simulating a TL494-based boost converter with slope compensation, or add a second error amplifier to implement overcurrent protection. Once the waveforms look clean, build a prototype, and you’ll find that the real circuit behaves remarkably close to your LTspice simulation.
: Connect Pin 13 ( OUTPUT CTRL ) to Pin 14 ( REF ) to enable push-pull mode . Tie it to ground for single-ended parallel mode . 4. Designing the Oscillator Frequency The internal oscillator frequency ( foscf sub o s c end-sub
Simulating the TL494 in LTspice is a "right of passage" for anyone designing push-pull, half-bridge, or full-bridge converters. Since the TL494 isn't always in the native LTspice library, users typically rely on third-party models (like those from The Pros: Why It’s Useful High Control Granularity
Double-check your .include path directive. Ensure the filename matches perfectly (e.g., .sub vs .lib ). Use the TL494’s dual outputs with an alternating
If you need to create your own symbol, map these pins:
because the steering flip-flop divides the frequency by two:
Click Simulate -> Edit Simulation Cmd .
The community-driven nature means that model errors have been identified and corrected over time. The “V§DT” corruption and AND gate syntax issues documented in 2023-2024 are the most recent examples of this collaborative debugging process. LTSpice is widely used by designers and engineers
Use the standard TL494 timing formula to calculate your target components:
Remember the golden rules:
The TL494 features two operational amplifiers with inputs at Pins 1 & 2 (Amp 1) and Pins 15 & 16 (Amp 2). The outputs of these amplifiers are logically OR-ed together at the Feedback pin (Pin 3).
You can find third-party TL494 models from community sources:
7 = CT 8 = RT 9 = GND 10 = C1 11 = C2 12 = VCC