Texas Instruments provides a PSpice model for the TL494. While PSpice models often work in LTspice, they require conversion. Download the .lib or .cir file from TI’s website, then use the .include directive in LTspice.
Steps:
Warning: Some TI models contain encrypted nodes or syntax that LTspice rejects. You may need to fix line breaks or comment out analog behavioral modeling (ABM) statements.
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.
To accurately simulate the device, one must understand its four distinct internal blocks.
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. tl494 ltspice
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.
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)
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. Texas Instruments provides a PSpice model for the TL494
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.
is a versatile Pulse-Width Modulation (PWM) control circuit widely used in switch-mode power supplies (SMPS) for its fixed-frequency operation and dual output capability. Integrating it into Warning: Some TI models contain encrypted nodes or
is essential for power electronics design, though it requires specific handling due to the lack of a native model in the standard LTspice library. MK Dynamics Availability of TL494 LTspice Models no official LTspice model
provided by the manufacturer (Texas Instruments). Designers typically rely on the following: MK Dynamics Third-Party Subcircuits : Unofficial models, such as those found on MK Dynamics or community forums like LTspice@groups.io , are commonly used. PSPICE Conversions
: Models designed for PSPICE (often found in OrCAD libraries) can be imported into LTspice by manually creating a matching schematic symbol. Subcircuit Structure
: A typical TL494 subcircuit includes internal components like two error amplifiers, a sawtooth oscillator, a dead-time control (DTC) comparator, and output steering flip-flops. How to Integrate TL494 into LTspice
To use a TL494 model in your simulation, follow these steps: Electronics - Hacking the TL494 LTSpice Model - MK Dynamics
Before touching a soldering iron, simulation answers critical questions:
LTSpice is the ideal platform because it handles transistor-level nonlinearities and switching transients better than many paid tools—and it’s free.
Texas Instruments provides a robust TL494 PSpice model. While PSpice and LTSpice have different syntaxes, you can convert or directly use the .lib file.
Would you like an example LTspice schematic file (.asc) for a basic TL494 buck or boost converter simulation?