Tl494 Ltspice __link__ Jun 2026

PWM comparator: compare error amp output to oscillator Bpw OUT 0 V= ( V(COMP) > VOSC ? Vcc : 0 ) .ends TL494_BHV .endcode

Ground the OC pin for push-pull, or connect to VREFcap V sub cap R cap E cap F end-sub for single-ended.

Instructions on how to perform a to test your loop stability.

A unique feature of the TL494 is the Dead-Time Control pin. It sets the minimum dead time (off-time) for the output transistors. This prevents "shoot-through" current in push-pull or bridge topologies. tl494 ltspice

* TL494.sub * Connections: 1IN+ 1IN- FB DTC CT RT GND C1 E1 E2 C2 VCC OC REF 2IN- 2IN+ .subckt tl494 1IN+ 1IN- FB DTC CT RT GND C1 E1 E2 C2 VCC OC REF 2IN- 2IN+ [SPICE model code omitted for brevity; see references [1, 3] for full listing] .ends tl494 Use code with caution. Copied to clipboard 2. Implementation Steps

Expected waveforms:

Users updating to LTspice24 have reported errors with the AND gate models used inside the TL494 subcircuit. Specifically, lines like: PWM comparator: compare error amp output to oscillator

The TL494 is primarily voltage-mode. However, you can implement current-mode by feeding the current sense signal into the second error amplifier (pins 15/16) and OR-ing it (via diode) to the compensation pin. Simulating this requires careful tuning of the current ramp slope compensation to avoid subharmonic oscillations.

The next time you reach for the TL494 datasheet, open LTspice first. With the right model and the knowledge from this guide, you’ll have your PWM controller simulated and optimized before building a single prototype.

Once you place the TL494 symbol onto your schematic canvas, you must properly configure its external timing and control pins to establish a functional simulation baseline. A unique feature of the TL494 is the Dead-Time Control pin

LTSpice doesn’t include a built-in TL494 device, so you have three realistic options:

To create a variable PWM signal, inject a DC voltage into pin 3 through a resistor (e.g., 1kΩ). By sweeping this voltage, you can observe the PWM duty cycle change.

This pin dictates the output topology:

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.

Configure a transient analysis to observe the startup behavior of the chip: Click > Edit Simulation Cmd . Select Transient and set the Stop Time to 5ms . Place a voltage probe on Pin 5 ( CTcap C sub cap T ) to observe the clean, linear sawtooth ramp.