Patent ID: 8503140

Claim:
A device comprising: symmetrical bi-directional back-to-back stacked silicon controlled rectifiers (SCRs), comprising: an anode of a first of the back-to-back stacked SCR connected to an input, an anode of a second of the back-to-back stacked SCR connected to ground, and cathodes of the first and second of the back-to-back stacked SCR connected together, wherein each of the symmetrical bi-directional back-to-back SCRs include a pair of diodes directing current towards the cathodes which, upon application of a voltage, become reverse biased effectively deactivating elements from the first symmetrical bi-directional back-to-back SCRs while the diodes of the second symmetrical bi-directional back-to-back SCRs direct current in the same direction as the reverse biased diodes.