LTspicePowerSim

Synchronous buck — PI regulation

LTspicePowerSim's 5 V to 1 V synchronous buck, its compensator and PWM block replaced by a PI-controlled switch.

Press Run: the example simulates in your browser. Open and simulate takes it to the full app, where you can change it.

Try this

Change the voltage reference from 1 V to 1.2 V and watch the duty follow. Then press Run again.