A semiconductor device has a protected node and a reference node, and a bi-directional ESD structure electrically coupled between the protected node and the reference node. The bi-directional ESD structure includes a main transistor electrically coupled between the protected node and the reference node, an upper control transistor with current nodes electrically coupled between the protected node and a control node of the main transistor, and a lower control transistor with current nodes electrically coupled between the reference node and a control node of the main transistor. The bi-directional ESD structure also includes an upper trigger network configured to provide a transient on-state signal to the upper control transistor from a positive electrical pulse on the protected node. The bi-directional ESD structure further includes a lower trigger network configured to provide a transient on-state signal to the lower control transistor from a negative electrical pulse on the protected node.