Tl494 Ltspice ›

The TL494 is a classic PWM controller widely used for switch-mode power supplies, battery chargers, and motor drives. This post shows how to simulate the TL494 in LTSpice, explains a basic application (a simple buck converter), and gives tips for accurate results.

Some engineers use the LTC3892, a modern controller from ADI. However, its behavioral model does not match the TL494’s discrete logic, leading to inaccurate dead-time and error amplifier responses.

Would you like an example LTspice schematic file (.asc) for a basic TL494 buck or boost converter simulation?

Feature: Simulating a TL494-based Boost Converter with Voltage Mode Control

Circuit Description:

The TL494 is a versatile PWM controller that can be used in various power supply topologies, including boost converters. In this example, we'll simulate a boost converter with voltage mode control using the TL494. tl494 ltspice

Circuit Schematic:

You can create the following circuit in LTspice:

Simulation:

Observations:

Tips and Variations:

By simulating this circuit, you can gain insight into the operation of the TL494 and the behavior of a boost converter with voltage mode control. You can also experiment with different circuit parameters and component values to see how they affect the converter's performance.

The TL494 is a versatile PWM controller commonly used in switch-mode power supplies. Because it is not a native component in LTspice, using it requires importing a third-party subcircuit (.sub) and symbol (.asy) file. 1. Acquiring and Installing the TL494 Model

Since Texas Instruments does not provide an official TL494 SPICE model, you must use community-verified files:

Subcircuit File (.sub): This contains the mathematical TL494 SPICE model.

Symbol File (.asy): This provides the visual component for your schematic. You can find a compatible TL494 symbol on GitHub. Installation Steps: Place the .sub and .asy files in your project folder. The TL494 is a classic PWM controller widely

In LTspice, go to Edit > SPICE Directive and type .include tl494.sub to link the model.

Open the component selector (F2) and select your .asy file to place the IC on the schematic. 2. Core Simulation Features

The TL494 model in LTspice allows you to simulate several critical functions: SPICE model for tl494 - Simulation (Ngspice)

LTspice needs a graphical symbol to represent the text model.

LTspice does not include a TL494 model by default. You have three options: Simulation:

Once your simulation runs, use LTspice’s powerful analysis tools to refine your design:

The TI PSpice model uses charge-controlled switches. Add options reltol=1e-3 vntol=1e-4 to your simulation directive.