Patent ID: 8300373

Claim:
A circuit for blocking electrical transients, the circuit comprising: a current-protective subcircuit comprising two metal oxide semiconductor (MOS) transistors and a junction field effect transistor (JFET) connected in series such that the JFET is between the MOS transistors, and such that the JFET and the MOS transistors automatically switch to a non-conducting state when a current passing through the current-protective subcircuit between a circuit input and a circuit output exceeds a predetermined current threshold magnitude; a first voltage comparison subcircuit connected to a gate of the JFET and capable of providing a gate voltage to the JFET to switch the JFET to a non-conducting state, thereby also switching the MOS transistors to a non-conductive state; wherein the first voltage comparison subcircuit has a first input that is connected to the current-protective subcircuit to facilitate measurement of an output voltage at the circuit output and a second input that is connected to a first external voltage source; wherein the first voltage comparison circuit switches the JFET to a non-conductive state if the output voltage at the circuit output when compared to the first external voltage source falls outside a first predetermined voltage range; whereby the circuit is capable of blocking transients having a transient current that exceeds the predetermined current threshold magnitude and/or having a transient output voltage outside the first predetermined voltage range.