I have a SMPS which I would like to current limit. The current limiter should have a negligible voltage drop when not limiting (say, <0.5%). I thought of inserting a MOSFET and a hall-effect current sensor in series, and switch the MOSFET on and off up to 20kHz to limit the current to a certain value when it is reaching that value. The output would be smoothed out by a capacitors.
Is it going to work? The SMPS is switching at about 50kHz, providing an adjustable voltage between 1.2V and 12V, and the current limit should be settable between 10mA and 5A.
What transistor should I choose for the job (what considerations etc.)?