Electronic Fuse

by VladM

26 parts

An electronic fuse measures the current and opens a switch past a limit and, unlike a fuse, it can be re-armed. Drag "load" (top left): past 5A the shunt amplifier U1 (10 mΩ × gain 50 = 0.5 V per amp) crosses 2.5 V, U2 sets the latch, and Q1 opens. Lower the load, then press "reset" (under the latch) twice: the push-button latches, once to close it and once to open it. Above it, F1 is the solver's fuse part at the same 5A rating, with its own "fuse load": drag it past 5A and F1 opens for good. To restore it, bring "fuse load" below 77 % and press ↺ which restarts the whole circuit from zero (re-arming the e-fuse too) and leaves the sliders where they are. Real systems: a 12 V e-fuse at 5 A protects a 60 W load; its sense resistor dissipates 0.25 W at the limit, the same as here.