Circuits, integrated circuits, apparatuses, and methods, such as those for protecting circuits against electrostatic discharge events are disclosed. An example apparatus comprises a thyristor coupled to a node and configured to limit the voltage and discharge the current associated with an over-voltage event at the node. The over-voltage event includes a negative voltage having a magnitude that exceeds a trigger voltage of the thyristor. The example apparatus further comprising a transistor coupled to the thyristor and configured to adjust the magnitude of the trigger voltage.