Tl494 Ltspice -

In your LTspice schematic, use the SPICE directive tool (press 'S') and add: .include TL494.sub . Step 2: Creating the LTspice Schematic with TL494

Add an initial condition directive to your schematic to kickstart the capacitor: .ic V(CT)=0 tl494 ltspice

.tran 0 5m 0 10n startup

Some poorly coded third-party models fail to regulate the 5V REF pin properly if the simulation supply ramp is too steep. Ensure your VCC source has a realistic rise time (e.g., 100 microseconds) rather than an instantaneous ideal turn-on step. In your LTspice schematic, use the SPICE directive

Run the simulation. Probe the collector output pins. You should see a PWM signal at ~11 kHz. Vary the voltage at the non-inverting input of error amplifier 1 (pin 2) to see duty cycle modulation. Run the simulation

Oscillator frequency approx determined by RT/CT

| Step | Action | Key Points | For More Details | | :--- | :--- | :--- | :--- | | | Obtain a Model | Find a reliable third-party model (e.g., from Valentyn Volodin). | | | 2. Setup | Install Correctly | Place the .asy file in sym and the .sub file in lib . | | | 3. Base Config | Set Basic Pins | Connect Vcc to supply, GND to ground. Connect DTC to GND to disable minimum dead-time. | | | 4. Output Stage | Add Pull-up Resistor | Use a resistor from output pin (e.g., E1 ) to a positive supply. | | | 5. Oscillator | Configure Frequency | Connect RT and CT to set switching frequency: f ≈ 1.2 / (RT * CT) . | | | 6. Feedback | Manage Error Amps | Disable unused error amplifiers by tying -IN to Vref and +IN to GND. | | | 7. Simulation | Handle Convergence | Use the Alternate solver if you encounter time-step errors. | | | 8. Testing | Verify PWM Output | Check for a clean PWM waveform at the output; troubleshoot using steps 3-7 if missing. | | | 9. Application | Build Converter Circuit | For a buck converter, replace the MOSFET with an ideal switch to aid convergence. | | | 10. Practical Use | Learn from Community | Consult forums like StackExchange and All About Circuits for troubleshooting specific issues. | |