Change your simulation command to start external supplies at zero volts by checking the "Start external DC supply voltages at 0V" option ( .tran 10m startup ). Time-Step Too Small / Convergence Errors
To make the TL494 model oscillate and function in your simulation, you must configure its timing, dead-time, and output mode networks.
For (e.g., Buck or Boost), the output switching frequency equals the oscillator frequency: tl494 ltspice
Below is a functional SPICE model for the TL494 that can be used in LTspice. Copy the text below and save it as a file named TL494.sub in your LTspice library folder (typically C:\Users\<User>\Documents\LTspiceXVII\lib\sub ).
: A full buck converter simulation will include the TL494 controller, a gate driver, a power MOSFET, an inductor, a capacitor, and a feedback network. The feedback network is critical: it typically divides down the output voltage and feeds it to one of the error amplifiers on the TL494. A reference voltage (e.g., from a TL431 or a simple voltage divider from the 5V REF pin) is fed to the other input of the error amplifier. The error amplifier’s output then drives the FB pin, closing the loop. For initial simulation, you can replace the power MOSFET with an ideal voltage-controlled switch. This simplifies the model, makes the simulation run much faster, and eliminates any convergence issues related to a specific MOSFET’s SPICE model while still allowing you to test the control loop. Change your simulation command to start external supplies
In your LTspice schematic, use the SPICE directive tool (press 'S') and add: .include TL494.sub . Step 2: Creating the LTspice Schematic with TL494
The PWM duty cycle is determined by comparing the control voltage on the FB pin (pin 3) with the sawtooth waveform on the dead-time comparator. As the voltage on pin 3 increases from 0.5V to 3.5V, the duty cycle can vary from 0% to nearly 100%. Copy the text below and save it as a file named TL494
If you tell me what specific converter type you are building (Buck, Boost, Push-Pull), I can provide a detailed schematic snippet or help you optimize your compensation loop . Share public link
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