In the Econoline regulated series, how exactly does the current limiting function operate?
A series resistor in the main FET driver circuit acts as a current sensor. As the FET source current increases, so does the volt drop across this resistor. The feedback regulation circuit is referenced to the series resistor rather than to GND, so as the resistor voltage increases, the converter is automatically throttled back. The net effect is that the combination of output voltage sense and input current sense creates a feedback system with approximately constant power.
