An SCR and protection method are provided to prevent the latch up and electrostatic discharge voltage breakdown and to protect circuit from the electrostatic discharge. The first PNP transistor(Q1) comprises the emitter connected to the first node. The first resistance is connected to the base and voltage source of the first PNP transistor. The NPN transistor(Q2) comprises the base connected to the collector connected to the base of the first PNP transistor and the collector of the first PNP transistor and the emitter connected to the second Node. The SCR(14) is comprised of the first PNP transistor and NPN transistor. The voltage source controls the trigger voltage of SCR by biasing the base of the first PNP transistor.
