In the previous example, the TSM36A is protecting an IO Link tranceiver that has a nominal voltage of 24 V and a maximum input voltage of 30 V. Most industrial interfaces such as this require protection against ±1 kV surge test through a 42-Ω coupling resistor and a 0.5 µF capacitor, equaling approximately 24 A of surge current. If a surge event caused by lightning, coupling, ringing, or any other fault condition occurs without any input protection, then this input voltage will rise to hundreds of volts in microseconds, which violates the absolute maximum input voltage and will harm the device. An ideal surge protection diode will maximize the useable voltage range while still clamping at a safe level for the system.