An apparatus including an electrostatic discharge (ESD) protection device comprising a semiconductor having first, second and third regions arranged to form a transistor, wherein the first region is doped with a first impurity of a first conductivity type and is separated from the second region which is doped with a second impurity of a second conductivity type opposite the first type, and wherein a dimensional constraint of the regions defines an operational threshold of the ESD protection device. In one example, the separation between a collector and an emitter of a bipolar transistor defines a trigger voltage to cause the electrostatic discharge protection device to become conducting. In another example, a width of a bipolar transistor base controls a holding voltage of the electrostatic discharge protection device.