Tl494 Ltspice _verified_ Jun 2026

* Dead Time & PWM Logic (Pin 4) * Dead time voltage effectively offsets the sawtooth floor or clamps the comparator. * If V(4) > Sawtooth, Output is OFF. * Effective PWM comparator: Duty Cycle = (V_saw - V_dead) / V_saw_amp.

Dead-time control (pin 4 = DTC, but we simplify via comparator offset) E_DTC 120 0 VALUE 0.1 ; fixed ~10% dead time

To implement a safe margin preventing shoot-through in half-bridge configurations, create a voltage divider from (Pin 14) to provide roughly 0.1V to 0.3V to the DTC pin. Selecting Output Modes

Before diving into the simulation files, let’s recap the key features of the TL494 that matter in LTspice: tl494 ltspice

Use .ic directives to set initial voltages (e.g., .ic V(out)=0 ) to simulate the turn-on phase.

to ground upon power-up, ramping up the duty cycle smoothly without blowing virtual fuses. Step-by-Step Simulation Walkthrough

Available on GitHub's sunnyiisc Spice Collections or via customized fixes on MK Dynamics . * Dead Time & PWM Logic (Pin 4)

—often found in community forums or educational repositories. Move the Subcircuit File : Place the

The TL494 can achieve duty cycles up to nearly 100% (typically 96%) in single-ended mode, or 50% in push-pull mode, with dead time controlled by the DTC pin voltage.

| Error Message | Likely Cause | Solution | |---------------|--------------|----------| | "Time step too small" | Fast switching + floating node | Add 1MEG resistors from each output to GND. Reduce maxstep in .tran . | | "Singular matrix" | Missing DC path to GND | Check the voltage feedback divider; ensure error amp inputs are not floating. | | Output always high or always low | Dead-time pin too high (>3V) or wrong oscillator | Set DTC <0.6V for max duty cycle. Verify RT/CT values. | | No oscillation at pin 5 | Missing ic initial condition | Add .ic V(osc_pin)=0.3V or use startup flag. | Dead-time control (pin 4 = DTC, but we

Output Transistors (Open Collector) Q1 8 104 9 NPN Q2 11 104 12 NPN .MODEL NPN NPN

.ENDS TL494

Set up the to regulate the output voltage, typically using a voltage divider from the output to 1IN- . Step 3: Running a Transient Simulation To see the PWM signals:

Locate a .subckt file for the TL494. If you have the raw text code, follow these steps: Open a text editor (like Notepad). Paste the TL494 SPICE text code.