This slide outlines the critical parameters engineers need to understand to select the appropriate protection device. Working voltage is the maximum voltage the data signal can be without the ESD protection device responding like it would during an ESD event. The breakdown voltage, which is above the working voltage, is the voltage at which the protection diode will begin to respond and begin to clamp the signal it is protecting towards ground. The clamp voltage is the voltage the system/end-equipment will have to be able to survive during an ESD event (much lower than the actual ESD voltage). For example, consider an ESD protection device that has a clamp voltage of 14 V. If that device is protecting a USB port from an 8000 V ESD strike, the ESD protection device would be able to clamp the 8000 V event on the USB data pins down to 14 V. That means the USB transceiver, and the rest of the system, only needs to be able to survive 14 V for a short period of time. Make sure the devices being selected meet the minimum ESD and surge protection requirement. Surge can be thought about as a long ESD event; ESD events are measured in the nanosecond range and surge events are measured in the microsecond range. The last parameter is leakage current. When using an ESD protection solution it will be placed in parallel with the data lines. Unfortunately, all ESD protection solutions will leak some amount of current onto the data line which creates noise and impacts signal integrity. The designer will want to choose a device with low leakage.