Simpler ways to develop a buck regulator
It appears to be a hysteretic buck regulator. Please see link for more details. Briefly, the switch turns on if the output voltage is lower than the setpoint, and off once the output voltage rises again.

There will be an output voltage oscillation around the setpoint, so this type of regulator is not suitable for applications sensitive to some ripple. It's a cheap solution, and sounds interesting for your application.