Tl494 Ltspice |link| Jun 2026

A4 0 020 0 N008 0 0 N006 0 AND vhigh=4.8 td=50n E1 020 0 OC 0 1

Since the TL494 is a mixed-signal IC (incorporating analog comparators and digital logic), a functional behavioral model is used rather than a detailed transistor-level schematic.

Outputs drive MOSFET (simplified) R_GATE OUT1 0 100 R_GATE2 OUT2 0 100

Save the file as tl494.lib or tl494.sub inside your LTspice library folder ( C:\Users\ \Documents\LTspiceXVII\lib\sub ). Step 2: Create the Symbol ( .asy )

Feedback input (pin 5) overrides if lower D_FB 5 6 DCLAMP .MODEL DCLAMP D(Vfwd=0.7) tl494 ltspice

: The LTspice Group contains extensive collections of models and example schematics.

: Place a series resistor-capacitor network (Type II compensation) between Pin 3 ( FEEDBACK ) and Pin 2 ( 1IN- ) to stabilize the error amplifier loop and prevent simulation oscillations. 7. Troubleshooting Common LTspice TL494 Errors Error: "Unknown subcircuit / Cannot find definition"

Based on community experience, here’s a summary of best practices:

Save the model text as TL494.sub in the same directory as your LTspice schematic. A4 0 020 0 N008 0 0 N006 0 AND vhigh=4

(Note: The code above is a high-level abstraction. For precise engineering, utilize the official Texas Instruments PSpice model.)

The TL494 subcircuit contains many internal nodes and A-devices, which can slow down transient simulations — especially when driving MOSFETs through gate drive transformers.

Connect to GND for minimum dead time, or to a small voltage to set a specific dead time.

The is the backbone of legacy switch-mode power supplies (SMPS), and simulating it in LTspice allows you to design, test, and troubleshoot complex power topologies without frying physical components. : Place a series resistor-capacitor network (Type II

Directs the modulated pulse to alternating output transistors when configured for push-pull mode, or switches them simultaneously in parallel single-ended mode.

: Like many complex switching models, the TL494 can sometimes cause LTspice to slow down or throw "Time step too small" errors during high-frequency transitions. Idealized Behavior

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