Electrical – Protecting external power lines from short circuit


Sadly i am only a software engineer with little electronic knowledge. I build a device with a mcu and a 5-pin connector (3.3v, Gnd, 3 data lines) on it. My mcu has a 3.3v supply pin which i connected to my 5-pin connector to supply some external sensors. Everything works fine.

My question now is there any kind of best practise to protect these external supply lines against short circuit? (The mcu is very expensive so i really want to protect it). I mean users don't always are that careful with your product than you hope. Also the product will be used outdoors.

EDIT: I realised i might have asked the wrong way. Maybe it is easier to ask the following question: Whats the common way manufactures of electronic devices with external connectors protect their devices from bad usage? (for example user attaches damaged cable)

Best Answer

A low voltage drop solid state series current limiter can be constructed. It's a constant current pushing circuit that tries to push(* the maximum allowed load current. It's the same as in power supplies that have a linear regulator.

Check, if your system already has a current limiter in 3.3V output.

*) no active pushing, only no limiting until the load tries to sink too much current

Maybe you should to think to add a robust extra power supply for external stuff. This would be my solution. Note: you have to protect your data lines, too!

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