TPD4E004: Resistor for current limitation

Machida-

You're correct the resistor is for current limiting. When an ESD strike occurs, the ESD device will clamp the pulse significantly but it cannot clamp it completely. This means that often an 8kV pulse for example would be clamped to 30V. Because this 30V is still higher than the protected lines supply voltage some current will flow through the line into the protected device. By placing a series resistor on the line, this current is limited to below the max input current of the protected device.

I would recommend adding a series resistor, but for specifics you can calculate the proper value by looking at the datasheet for the device that is being protected and seeing what the max input current is and the supply voltage, then looking at the TD4E004 Rdynamic specification to see what the voltage will clamp to at the maximum tested ESD strike. Once you have those values, you should be able to calculate the required series resistance to ensure that the current specification of the protected device will not be violated during an ESD strike.

Does that answer your question?

Thanks,
Alec