Hi!
I'm building a bench power supply and i need some kind of output overcurrent protection. I want when a certain set current is exceeded the output to be turned off. The current detection circuitry is done, i can detect the current, but i'm still figuring out how to turn of the output. First i tough of simple relay, but they can have very high contact resistance and will drop too much voltage. Now i'm thinking about a way to probably use a N-channel MOSFET to turn of the high side of the power supply because there are some that are cheaper that relays and have much lower on resistance. I'm not very experienced with MOSFETs and i don't know will this be a simple circuit with one transistor and some resistors or are there some oscillation problem than need to be taken in consideration. The output of the power supply is 1.2V-26V 2.5A maximum. So i guess the MOSFET should be able to operate with a minimum voltage between the drain and the source of 1.2V. Will this be a problem? Everything is being monitored by a microcontroller, so when the current limit is reached it will send a signal to the MOSFET, or rather it will turn of the signal depending on the transistor type. Can you recommend some simple standard circuit and some common MOSFET with low on resistance (lets say <0.005ohm). Thanks!