A traditional overvoltage protection scheme consists of a fuse, silicon controlled rectifier (SCR), and zener diode. Once the input supply voltage exceeds the zener breakdown voltage, the SCR activates, drawing sufficient current to blow open the upstream fuse. While this circuit is simple and inexpensive, it is not suitable for modern digital logic operating from low voltages. The response time of the zener diode, SCR diode and fuse are not certain. Furthermore, the SCR diode’s forward voltage drop may already be higher than that permitted by the FPGA. After fault, system recovery is cumbersome with someone having to physically replace the fuse.