Connect the OUTPUT pin to a 33µH power inductor, followed by a 220µF smoothing capacitor connected to ground.
Standard Proteus components often lack the internal intelligence or VSM (Virtual System Modeling) properties required to simulate switching dynamics. A high-quality or "extra quality" library contains: lm2596 library for proteus extra quality
A reputable source for custom Proteus libraries. They often provide high-quality, ready-to-use models, including the LM2596 with 3D views. Connect the OUTPUT pin to a 33µH power
C:\ProgramData\Labcenter Electronics\Proteus 8 Professional\Data\LIBRARY (Note: The "ProgramData" folder is hidden by default in Windows. You may need to enable "Show hidden files" in File Explorer.) lm2596 library for proteus extra quality