2 Basic operations of TVS diodes (ESD protection diodes)

ESD protection diodes are inserted between signal lines and GND in order to protect a device under protection (DUP) from voltage surge. In normal operating mode (i.e., in the absence of an ESD surge), little current flows through the ESD protection diodes, except a very small amount of current (I_R) that flows through the diodes that sets their reverse breakdown voltage (V_BR) to a level higher than a signal line. When a voltage surge higher than the reverse breakdown voltage (V_BR) is introduced into a signal line, the ESD protection diodes shunt excessive current to GND, suppressing the surge voltage below the reverse breakdown voltage (V_BR).